Male pattern baldness is caused by DHT, a byproduct of testosterone that binds to your hair follicles and starves of them of nutrients, making them shrivel up and die.
5-alpha reductase inhibitors like finasteride/dutasteride inhibit production of DHT but leave testosterone alone if you want to keep your hair and like being a man.

Transgender people have more options, they're all scorched earth though, they just nuke testosterone completely, which also nukes the DHT pathway too.