Expand single menu and automatically collapse other menus in SwiftUI

Consider this simple approach:

Create a @State var in your AnalyzeView called expandedId that is of type UUID. Share this on to both of your child views via Binding. In the child views, when you expand, set this id to one stored in your child view. React to changes of this id in your child views and if they don´t match the one stored set the collapsed var to true.

struct Collapsible_main<Content: View>: View {
    @Binding var expandedId: UUID // add this
    
    @State var label: () -> Text
    @State var content: () -> Content
    
    @State private var collapsed: Bool = false
    
    private let id = UUID() // add this
    
    var body: some View {
        VStack {
            Button(
                action: {
                    self.collapsed.toggle()
                    if !self.collapsed{
                        self.expandedId = self.id
                    }
                },
                label: {
                    HStack {
                        self.label()
                        Spacer()
                        Image(systemName: self.collapsed ? "chevron.down" : "chevron.up")
                    }
                    .padding(.bottom, 1)
                    .background(Color.white.opacity(0.01))
                }
            )
            .buttonStyle(PlainButtonStyle())
            
            VStack {
                self.content()
            }
            .frame(minWidth: 0, maxWidth: .infinity, minHeight: 0, maxHeight: collapsed ? 0 : .none)
            .clipped()
           // .animation(.easeOut)
            .transition(.slide)
        }
        .onChange(of: expandedId) { newValue in
            if newValue != self.id{
                self.collapsed = true
            }
        }
    }
}

struct Collapsible_other<Content: View>: View {
    @Binding var expandedId: UUID // add this
    
    @State var label: () -> Text
    @State var content: () -> Content
    
    @State private var collapsed: Bool = true
    
    
    private let id = UUID() // add this
    
    var body: some View {
        VStack {
            Button(
                action: {
                    self.collapsed.toggle()
                    if !self.collapsed{
                        expandedId = self.id
                    }
                },
                label: {
                    HStack {
                        self.label()
                        Spacer()
                        Image(systemName: self.collapsed ? "chevron.down" : "chevron.up")
                    }
                    .padding(.bottom, 1)
                    .background(Color.white.opacity(0.01))
                }
            )
            .buttonStyle(PlainButtonStyle())
            
            VStack {
                self.content()
            
            }
            .frame(minWidth: 0, maxWidth: .infinity, minHeight: 0, maxHeight: collapsed ? 0 : .none)
            .clipped()
           // .animation(.easeOut)
            .transition(.slide)
        }
        .onChange(of: expandedId) { newValue in
            if newValue != self.id{
                self.collapsed = true
            }
        }
    }
}


struct AnalyzeView: View {
    
    @State var listingValue: Double = 200000
    @State var unitsValue: Double = 2
    @State var sqftValue: Double = 3000
    @State var downPaymentValue: Double = 100000
    @State var loanValue: Double = 10000
    @State var pmiValue: Double = 700
    @State var interestValue: Double = 0.02
    @State var closingValue: Double = 14000
    
    @State private var expandedId = UUID()
    
    var body: some View {
        
        VStack {
            
            ZStack() {
                
            Image("analyze_property")
                .resizable()
               // .aspectRatio(contentMode: .fit)
                .scaledToFit()
                
                RoundedRectangle(cornerRadius: 30, style: .continuous)
                    .fill(.blue)
                    .opacity(0.8)
                    .frame(width: 300, height: 170)
            
                VStack {
                    Image("gauge")
                    
                    Text("Analyze")
                        .foregroundColor(.white)
                        .font(
                            .largeTitle
                            .weight(.bold)
                        )
                    
                    Text("Return On Investment")
                        .foregroundColor(.white)
                }
                
            }
            
            Collapsible_main(
                // pass the id on
                expandedId: $expandedId, label: { Text("Property Information").font(.largeTitle) },
                
                content: {
                    
                    VStack(spacing: 20) {
                    
                        Group {
                            
                        Text("Enter your property info below. The more data you provide the better we can analyze.").frame(maxWidth: .infinity, alignment: .leading).fixedSize(horizontal: false, vertical: true)
                            
                        }
                    
                            Text("Listing Price")
                            Slider(value: $listingValue, in: 0...10000000, step: 1){
                            } minimumValueLabel: {Text("0")} maximumValueLabel: {Text("$10M")} .background(Color.gray.brightness(0.4)).padding(.trailing, 50).padding(.leading, 50)
                            //Text("\(listingValue, specifier: "%.0f")")
                            
                            Text("Total Units")
                            Slider(value: $unitsValue, in: 0...20, step: 1){
                            } minimumValueLabel: {Text("0")} maximumValueLabel: {Text("20")}.background(Color.gray.brightness(0.4)).padding(.trailing, 50).padding(.leading, 50)
                            //Text("\(unitsValue, specifier: "%.0f")")
                            
                            Text("Square Feet")
                            Slider(value: $sqftValue, in: 0...15000, step: 1){
                            } minimumValueLabel: {Text("0")} maximumValueLabel: {Text("15K")}.background(Color.gray.brightness(0.4)).padding(.trailing, 50).padding(.leading, 50)
                            //Text("\(sqftValue, specifier: "%.0f")")
                        
                    }
                
                }
                
                )
        
            Collapsible_other(
                //pass the id on
                expandedId: $expandedId, label: { Text("Financials").font(.largeTitle) },
                
                content: {
                        
                        VStack {
                        
                            Text("Enter your financial data below.")
                            
                            Group {
                            
                            Text("Down Payment")
                            Slider(value: $downPaymentValue, in: 0...10000000, step: 1).padding(.trailing, 50).padding(.leading, 50)
                            Text("\(downPaymentValue, specifier: "%.0f")")
                            
                            }
                        
                            Group {

                            Text("Loan Amount")
                            Slider(value: $loanValue, in: 0...10000000, step: 1).padding(.trailing, 50).padding(.leading, 50)
                            Text("\(loanValue, specifier: "%.0f")")
                                
                            }
                            
                            Group {
                            
                            Text("PMI")
                            Slider(value: $pmiValue, in: 0...5000, step: 1).padding(.trailing, 50).padding(.leading, 50)
                            Text("\(pmiValue, specifier: "%.0f")")
                                
                            }
                            
                            Group {
                            
                            Text("Interest Rate")
                            Slider(value: $interestValue, in: 0...1, step: 0.01).padding(.trailing, 50).padding(.leading, 50)
                            Text("\(interestValue, specifier: "%.0f")")
                                
                            }
                            
                            Group {
                            
                            Text("Closing Cost/Fees")
                            Slider(value: $closingValue, in: 0...30000, step: 1).padding(.trailing, 50).padding(.leading, 50)
                            Text("\(closingValue, specifier: "%.0f")")
                            
                        }
                        
                    }
                    
                }
        
        )
            
            Spacer()
            
        }
        
    }
    
}