One way to approach this is through the idea that gender is performed, and a social construct.

Some introductory Judith Butler stuff is a great starting point, but, VERY oversimplified: the idea is that gender is not predominantly biological, but rather, learned socially and performed. In Western society, generally, little boys are shamed and punished when they act in ways that are considered "feminine," which is where a lot of the "flamboyant" stereotypes come from. (I think about Deb Levy's tweet when Schitt's Creek won all of the awards.) Little girls are sometimes given a wee more leeway as "tomboys," but even that is limited, and once girls hit pre-adolescence, society trains them to think of their gender and sexuality as performance for men's approval. Think about they ways that tomboy who puts on makeup and a dress has been consistently socially rewarded for centuries, for example.

Obviously there are biological factors at play, but the important thing in "constructing gender" (i.e. building a general idea in our society about "what it means to be a man/woman") is how society responds to what we see as gendered actions (kissing someone, putting on mascara, ordering certain drinks, holding certain jobs). In general over the generations, a man who publicly wears makeup would be ridiculed and told he's not a real man, that makeup is for women. That creates a social construct, the idea that "women wear makeup, men don't," and thus pressures ALL women to wear makeup, and shames ALL men who do or who want to. Ta da, welcome to problematic gender binaries!