Looking at the "Applies to" section in the documentation, this dialog was never defined for .NET Standard:
Applies to:
- .NET 5.0, 6.0 preview 3
- .NET Core 3.0, 3.1
- .NET Framework 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8
As further confirmation, if you select any version of .NET Standard in the "version" list on the left, you will get a message telling you that the requested page is not available.