I have opinions about this. Possibly more than most people, given recent experience. Here's what I'd actually change if I had the power to redesign the whole thing.
Start with the person, not the curriculum
The current model takes a fixed curriculum and attempts to deliver it to everyone in roughly the same way. The implicit assumption is that all brains learn the same things at the same pace through the same methods. This is obviously not true and the evidence for it not being true is every kid who doesn't fit and gets labelled as a problem rather than a signal that the system needs adjusting.
A better model starts by figuring out how a particular person learns, what they're interested in, and what they need — then builds around that rather than expecting them to fit around a fixed structure.
Practical skills that actually matter
How taxes work. How to read a contract. Basic financial literacy. How to find reliable information and evaluate sources. Basic cooking. Basic first aid. These are things almost every adult needs and almost no school teaches properly. The curriculum time spent on things most people will never use again could be partially redirected here.
Flexible pacing
Some people understand something quickly and are bored waiting for the rest of the class. Some people need more time and are stressed being rushed. The one-pace-fits-all model serves neither group well. Mastery-based progression — you move on when you've demonstrated understanding, not when the calendar says it's time — makes more sense. It exists in small pockets. It should be the norm.
Proper neurodiversity support
Not as an afterthought or a list of adjustments bolted onto a system that wasn't designed with different brains in mind. Actually built in from the ground up — different sensory environments available, different ways to demonstrate understanding beyond written tests, different ways to communicate. An autistic kid shouldn't have to fight for basic accommodations that should be standard.
Smaller environments
Large schools with hundreds of students in corridors between lessons are overwhelming environments for a lot of people. Smaller communities where you actually know the people around you would be better for most students and significantly better for those with sensory sensitivities. Scale is not a virtue in education.
What I'd keep
Some things are genuinely good. Good teachers — the ones who actually care and adapt — make an enormous difference. Exposure to subjects you wouldn't have chosen yourself occasionally produces unexpected interests. Social interaction with peers, when the environment isn't hostile, has real value. The institution has some things worth keeping. The structure around it needs significant rethinking.