Is it possible to create charts with .NET Core

Yes, you can do it as I did this.

1. Install into your WinForms core project Microsoft charts nuget
2. Install into your WinForms core project other nuget
3. Remark: Forms designer for charts in Winforms core projects will not work. But you can create a temporary Winforms .Net Framework project. Then create a chart by project form designer.
4. Then copy chart code into your first WinForms core project.

That's all you need.

Yes it's possible. You can get sample code here https://github.com/dotnet/winforms-datavisualization.

The line chart examples can be found in the folder sample/ChartSamples/ChartTypes/LineCharts.

Note: DataVisualization is deprecated

I do it by installing System.Windows.Forms.DataVisualization + System.Data.SqlClient

Don't use Forms designer for charts in Winforms core projects. Just create a new Winforms solution with .Net Framework (not core). Then create a chart in a new form by using designer you can adjust it as you want (colors, series...). Copy related chart code (from code behind cs) into your WinForms core project that's it.