You can play a male or female character without gaining any special benefits or hindrances. Think about how your character does or does not conform to the broader culture’s expectations of sex, gender, and sexual behavior. For example, a male drow cleric defies the traditional gender divisions of drow society, which could be a reason for your character to leave that society and come to the surface.
You don’t need to be confined to binary notions of sex and gender. The elf god Corellon Larethian is often seen as androgynous or hermaphroditic, for example, and some elves in the multiverse are made in Corellon’s image. You could also play a female character who presents herself as a man, a man who feels trapped in a female body, or a bearded female dwarf who hates being mistaken for a male. Likewise, your character’s sexual orientation is for you to decide.
This isn’t some kind of fan-made thing, this isn’t some obscure sourcebook for dealing with Controversial Topics. This is just in the basic game rules.
I have been pretty enthused about the 5e rules mechanically, but this was totally unexpected.