For example, if I waive my rights to know what you'll be doing with my internet search history, is that a knowing and intelligent waiver?
The question is rendered moot because Cal. Civ. §1798.100 declares that
Any provision of a contract or agreement of any kind, including a representative action waiver, that purports to waive or limit in any way rights under this title, including, but not limited to, any right to a remedy or means of enforcement, shall be deemed contrary to public policy and shall be void and unenforceable. This section shall not prevent a consumer from declining to request information from a business, declining to opt out of a business’s sale of the consumer’s personal information, or authorizing a business to sell or share the consumer’s personal information after previously opting out.
You can fail to request such information, and you can tell a business that you don't plan to ever exercise that right, but you cannot be bound by such promises, which is to say, this is an un-waivable right. For another right, you might be able to waive that right. Your 5th amendment rights can be waived, but we would have to know more of the circumstances to know if that was a knowing and intelligent waiver.