Gender dysphoria affects a vanishingly small percentage of a population (if we're going to go by human norms).
For Drow, I would think their society would outright ban sex changes, since sex is tied to power/caste. I'd expect it to be a "punishable by death on sight" issue.
For non-extremists like the Drow, I'd expect to see varieties of group dynamics concerning fluid sexual identities. You'd have those that change their sex on whim. You'd have those that believe it immoral to ever change your sex. You'd have those with gender dysphoria who'd bless the day they could afford the serum.
I bet orgies in Starfinder get crazy.