To me, ocassionally I have felt that sex has been kind of a communion with them in the right context during an evocation (specific spells like lust, or simply sex magic) or when they wanted to communicate and teach something through metaphors, and sex was part of the whole puzzle.
Otherwise, normally I don’t think sex itself is an offering or a way to get closer to an entity. Not because I reject the use of sex as a magic resource (please most here walk the LHP) but because, imo, it seems irrelevant to my magical practice.
Everything I do, say, practise or communicate with the entities has got a practical purpose. Unless sex has one of the meaningful purposes aforementioned, I consider it superfluous.
But hey, each one to his own.