I think that’s a false dichotomy though, because that assumes gender standards and presentations are universally consistent, when in practice it is often highly dependent on social context and individual perception.

What defines someone as masculine in the US is not 1:1 with the concept of masculinity in China, or France, or Kenya, for instance. On top of that, one’s personal understanding of masculinity and femininity likely differs slightly (or greatly) from the general standards of the society around them.

The easiest concept of gender is to just trust people when they tell you who they are. It’s entirely an internal, personal understanding of identity, and it’s mutable.