Is There Such a Thing as a Woman?

If gender isn't real and trans women are women, why do you need to take hormones? You should just be able to change your mind. It erases the whole idea of it. For some reason, this is the most chilling thing to me because it's so basic. And so not even just human, just on an animal level, I react to this. But they would say to you, well, what is your definition of a woman, then? Why do you get to decide what a woman is? Because it's been decided by biology long before. They know that biological sex is a thing. Otherwise they wouldn't fucking hope so. Or what do you need hormones for?