In older versions of Blender I have successfully used the Face Sets Extrude function in Sculpt mode.
According to this Video:
It is no longer available in version 4.0 of Blender!
Has it been removed without replacement, or is the functionality now in a different place?
Or is there another way to achieve the same thing?
Face sets were not removed, but I dont think or at least cant remind that Extude ever made it from the sculpt dev build to the mainbranch. So the most fitting answer is, that its not (yet) there.