Check the Visual Studio installer. There are many versions of .NET, and for Windows specific development like the old Windows Forms you need some options checked.
Then if you select the workload shown “.NET desktop development”, you should be good to go.
Under the hood, it will probably install the old .NET *Framework* (4.8) SDK, among other stuff.
In the new project templates, you’ll find it under “C# / Windows / Desktop” :
For completeness, see which individual components I have installed, I can create new windows forms with both .NET Framework 4.8 or with modern .NET 8 or .NET 9.
Here is the .csproj (I can open it directly in VS):
<Project Sdk="Microsoft.NET.Sdk">
<PropertyGroup>
<OutputType>WinExe</OutputType>
<TargetFramework>net8.0-windows</TargetFramework>
<Nullable>enable</Nullable>
<UseWindowsForms>true</UseWindowsForms>
<ImplicitUsings>enable</ImplicitUsings>
</PropertyGroup>
</Project>



