Tangentially, what is the limit of what can be put into a license or contract (that remains enforceable)? Can you just put any arbitrary requirements, as long a

Tangentially, what is the limit of what can be put into a license or contract (that remains enforceable)? Can you just put any arbitrary requirements, as long as it's not against the law? Like, if I lease my house, but with a clause that the resident should never change their name to "Jack" in their entire life, will that be laughed out of the court?