In an ideal world..
Young people actually being involved in the school, how it works for them, what they want from it. Participation at the highest level and not a tick box exercise.
What rules do they think their school needs? What behaviour plans do they think work? I would foster a sense of responsibility in the pupils of how they want their school to be ran. Young people would be consulted and listened too.
I'd get rid of uniform and have spare supplies in every room. Equipment shouldn't be in the way of learning and punishing dc for not having it is so alien to a work place that it doesn't make sense for schools to not provide it. It punishes those with chaotic homes and SEND.
I'd put all the teachers through a youth work degree to disemble the notion of strict and zero tolerance approach works best. Realise abuse of power that does happen and learn how building relationships work in managing behaviour.
I'd put more physical activity and learning through doing things. Sitting in a classroom if you're not a classroom person/learner is tough. The more bored dc are the more trouble they get into.
Natural consequences, you break something you work with the care taker to fix it.
Regulating behaviour, free breakfast club, free tea and toast at break. Longer breaks with more lunchtime clubs/football. We used to have an hour, now dc get 40 minutes, they need breaks.
We know that a child/adolescent brain is developing. There is a natural rebellious state that it goes through, there is a natural risk taking state again that it goes through. I'd stop forcing hours of boring classroom work by going back to longer breaks, outside classroom learning and PE. Taking away zero tolerance for uniform, kit, toilet breaks would remove a lot of conflict that escalates.
Also, I'd take away responsibility from the teachers and put it back on the yp. You can't force dc to do well. By the time they're 14 they know that if they don't pass their GCSEs life will be harder. I don't think it's healthy to have exam results as a way to measure schools - but I'd bet my house if I could run a school like that the natural result would be better attendance, less exclusions and good grades.