I never see in public git projects something like a declaration of scope. There's also no convention, unlike a README.md (which rarely contains some sort of scope definition) or LICENSE file.

Is this unusual in open source projects, that you first define what you want and not want in your project and how you want to do it, to combat scope creep and sabotaging yourself?

I'm in a postition in live (short of a burnout) where it's actively a pain to just start things and then wing it; i even add a scope comment to larger shell scripts.
Maybe it's experience, because i already know that i'm then not satisfied afterward or (in case of shell scripts) just create a unfinished mess.

Nobody else? Or am i looking for the wrong term?