My old public high school had pretty much no rules except the "No hats" rule, but nobody cared and it wasn't enforced. Of course, whenever /I/ wore a hat, it was, for some loving stupid reason, because they for some reason noticed me and nobody else.
My old Middle School principal (who was loving awesome) was moved over to my high school when I was going into 8th grade and I joined him the next year in 9th. The dress code was no longer enforced; my principal had no idea how to enforce it because he was a principal for younger schools his entire career so he just kinda let everyone do their own thing.
No PDA rules or anything (that were enforced) except when the new dean came in and started whining about everything and breaking up kids who were holding hands or kissing in the hallway. The teachers personally gave zero forgets about what the students did and the only one who cared about enforcing the rules was the new dean for the school.
It all worked out fine, though. All the students in the school liked to forget with her head to the point she gave up and stopped trying to act so tough and responsible. There was even a dedicated "Senior Skip Day" created and organized by all the seniors and on that day, all the seniors who participated (or remembered) skipped school for the entire purpose of giving the dean as much paperwork as possible. LOL
I left that school during my second semester of 10th grade and I'm in online school in the 11th grade now. Everyone there was turning into huge friends and I didn't enjoy it anymore.