From what I understand, the official way to detect Windows 11, is to look at the Operating System Build Number
I've read that a build number >= 22000 implies Windows 11
but I've found that it's better to check for >= 21966

Now how do get the OS build number in SetupBuilder.
I haven't tested this, but the help shows

Get System Info => Windows Build Number—The build number of the OS version. If the version was 5.00.2600, "2600" would be returned.

In Clarion....
IsWin11OrGreater PROCEDURE()!,BOOL
RETURN CHOOSE( SYSTEM{PROP:WindowsVersion, 5} >= 21966 ) ! 5 = BuildNumber

Mark Goldberg