True, but the NDA won't say 'I'll give you a million dollars if you don't mention that I trafficked and sexually abused you'.That's not correct. An NDA cannot cover any illegal activity.
It would say 'in return for a million dollars, you won't mention freely attending parties at my house, or any free holidays you took in my properties or ever being acquainted with me, and you agree to surrender all evidence of the same eg pictures on your phone'.
None of that is illegal, and that's how it's documented. Bear in mind that this is a contract signed voluntarily, in return for a lot of money, so the recipient of the cash has decided that's their best option rather than pursuing a criminal action, so they aren't likely to breach it.
Back the NDA up with a super injunction or two for something which overlaps, something legal but unsavoury enough to harm your good reputation, maybe swinging with consenting adults at the very same parties, and top it off with a reputation for being aggressively litigious....