Sure, I have started several relationships with sex.
I don’t underestimate animal magnetism, because I have very hairy goat legs, and I carry a flute. My lower half is connected to my upper, and it trods on hoofs rocks and dirt, and I smell of musk and exude pherermones. Pan.
If I didn’t want to consumate my lust on the first date, the chemistry lacked vigor. Not much reaction. Yin tepid and yang tepid. High school science class mentioned the formula that heat gained equals heat lost, meaning that the greater the temperature difference between hot and cold, the greater the exchange of energy.
So yes, sex on the first date. Means something. At least that part of the relationship works.