A company can craft whatever document they want. That doesn't make them legal. The laws of the jurisdiction they're in always beat whatever you're signing.

Best example in software are non competes.

A company can make you sign something that doesn't allow you to do any software development when you're a developer. You can sign that today then do the opposite tomorrow because that's just against the law.

See:

https://news.bloomberglaw.com/daily-labor-report/did-califor...