As someone who's played lots of video games they shouldn't have as a kid:

1) I always skipped the sex scenes. Look, teenagers know sex exist. We were not all a fan of it, but it doesn't give them psychic damage.

2) my parents have never forbidden me a game on the basis of optional sex scenes... and I don't know of any other who did, either. This is not what parents worry about.

3) as far as I can tell, the intended excluded audience is 7-13 year olds and 14-16 year olds respecting content ratings (a rare breed indeed).

There is no chance in hell Bg3 will lose profit on basis of having sex scenes. Let's be real here.