I am 54. I don’t think it is ever simple.
Men want 3 things (even if they don’t know it) in order of importance:
I really can’t stress this enough.
My advice for a woman dating online (or elsewhere) would be to state that you don’t have sex until after the 4th date no matter what. This should give you all the room you need to get what you need.
This will immediately weed out the guys that are not looking for a relationship (or are simply marking time until date 5).
Speaking for myself (sex is a big deal for me) I would totally respect that even if the sexual chemistry was off the charts after the first date because it is about respect. You’re telling him that you respect yourself. That is all he should need to hear. Or you can sleep with him. Own it.
I can tell you as a dating man that if I don’t pressure a woman for sex she actually gets offended! I’ve been called “Gay” simply because it wasn’t on the table yet for me. It takes the one powerful tool a women has to control a man off the table. They HATE that!