Uniforms would solve all of this. I wore a uniform from 1st through 12th grade and never had to worry about this stuff.
Having adults in charge would be even better.
While I never had a ‘uniform’, my schools always had a dress code (60’s). My parents took care of the dress code prior to that (50’s).
I’ve seen news clips off and on, some education specials, where the teachers/administration don’t even appear to have a dress code.