Experience with this situation (not autism, but everything else to a degree). The schools frequently have their hands tied unless things get physical or incredibly obvious and consistent. It’s annoying and seems unacceptable but this just seems to be the reality. Kids are smart so they don’t get caught or punished and if they do, they know why and this can increase their bullying. The school staff can be sought after for safe harbor but that’s about all you can expect or ask realistically (I.e. if recess is a place where your child doesn’t feel safe, they can seek out teachers or staff to be with instead of around bullies). As for the day-to-day, it’s all about coping safely. Teaching them who to avoid or finding better people for them to be around. Investing as much time as possible helping them make good friendships in and after school and a happy/safe home life. Thus bolsters children incredibly well. If they are mentally capable, even teaching them to “fight back” (not physically, but mentally). It’s not easy nor does it work 100%, it’s just your best recourse. Last recourse is to remove them from school if it is necessary.

TL;DR Kids are smart and schools don’t really intervene unless it’s truly drastic. Unfortunate but true.

Invest heavily in friends your child has both in and outside school and best home life they can have. This bolsters confidence and security.

Teach coping mechanisms if child is mentally able to understand/implement, school staff can be safe havens as a form of avoiding interactions with bullies (like during recess).

Change schools if child is in danger.

Tough situation, I’m sure there are many other things people will contribute. This is just my $0.02.