The ability to flirt or proposition in order to gain advantage is perfectly legitimate, and it's not uncommon at many game tables, though equally, it's not a done thing at others. I'm all for things like that being options
It’s not something I’d have thought to ask for, but I can see that if done in a non-creepy fashion flirting could be a potentially fun way to be able to deal with some situations (either when succeeding or being shot down in flames after a poor dice roll). Even more full on Mata Hari/James Bond seduction for underhand purposes, while of course problematic IRL, could be interesting. In fact, I’ll even confess to head-canoning my drow ranger from my “evil” Early Access playthrough to have slept with Minthara only to gain her trust, despite him being attracted to Astarion, so I guess I am in the market for being able to make some inappropriate use of sexuality for advantage in the game!
But personally I would need it to be done with consideration and without playing into old-fashioned stereotypes, rather than a bizarre indecent exposure mechanic that would be in equal parts disturbing, hilarious and impractical (especially for characters in full plate)!