This doesn't generally apply but Apple has a bunch of hardening in place that means you don't just have an RWX mapping hanging around:

https://developer.apple.com/documentation/browserenginekit/p...

On top of that they're working on (I haven't checked in a bit) having the JIT compiler be entirely Out-Of-Process. I don't think a lot has been written about that publicly but there's a few breadcrumbs like https://developer.apple.com/documentation/kernel/oop_jit_con...