MKGeodesicPolyline not dynamically changing size of map

I have a function that is adding a geodesic polyline on a great circle track between two points on a map. The issue I am facing is dynamically changing the size of the map to include both the start position and the end position.

Any tips on what I am missing here as I am setting the setVisibleMapRect???

Code below is for Melbourne Airport to Brisbane Airport with the result

var body: some View {
        MapView()
        .onAppear {
            self.mapRoute.toggle()
            self.updateMapOverlayViews()
            
         
        }
        .frame(height: 256)
        .cornerRadius(25)
        .padding()
   
}

func addRoute(latitudeStart: Double, longitudeStart: Double, latitudeEnd: Double, longitudeEnd: Double) {
    
    let c1 = CLLocation(latitude: latitudeStart, longitude: longitudeStart)
    let c2 = CLLocation(latitude: latitudeEnd, longitude: longitudeEnd)
    
    let zoom = c1.distance(from: c2)
    
    //Draws a MKGeodesicPolyline between the two points.
    var coordinates = [c1.coordinate, c2.coordinate]
    
    let geodesicPolyline = MKGeodesicPolyline(coordinates: &coordinates, count: 2)
    
    
    mapView.addOverlay(geodesicPolyline)
    let location = CLLocationCoordinate2D(latitude: (latitudeStart+latitudeEnd) * 0.5, longitude: (longitudeStart+longitudeEnd) * 0.5)
    
    let region = MKCoordinateRegion(center: location, latitudinalMeters: zoom, longitudinalMeters: zoom)

    let adjustRegion = mapView.regionThatFits(region)
  
    mapView.setRegion(adjustRegion, animated: true)
    
    mapView.setVisibleMapRect(geodesicPolyline.boundingMapRect, edgePadding: UIEdgeInsets.init(top: 80.0, left: 100.0, bottom: 100.0, right: 100.0), animated: false)
    
}


func updateMapOverlayViews() {
  mapView.removeAnnotations(mapView.annotations)
  mapView.removeOverlays(mapView.overlays)
    
    if mapRoute { addRoute(latitudeStart: -37.6690, longitudeStart: 144.8410, latitudeEnd: -27.3942, longitudeEnd: 153.1218) }
}

Result: