Pretty sure you are mistaken. Look up public policy violations. Typically you can't negotiate away rights

All contracts take away rights that the law explicitly guarantees you? Such confidence. Sometimes talking to an LLM is an improvement...

Of course. For example, the law guarantees that I don't have to perform labor for someone else if I don't want to. An employment contract obligates me to.

Similarly, it's entirely possible to enter into a contract limiting your freedom of speech.

The entire point of a contract is to promise to do, or not to do, something that you could have freely chosen to do or not to do under the law without any contract.