If you want to play the definition game, as this thread sets out to do, you really need to have regard to the distinctions the people who start talking about the thing are making.
Masculinity, as a manifestation of testosterone, has an inherent drive. Male H. Sapiens are naturally primed by the four f’s of evolutionary biology - you know, feeding, fighting, fleeing or (again, never mind). That Darwinian heritage — Wayfarer
What is inherent, what is evolved, what is natural, is called 'maleness', and 'masculinity' refers to social roles. The manifestations of testosterone include all things female: men have relatively elevated testosterone levels, and that is part of maleness.
Masculinity becomes toxic when men begin worrying about their masculinity. — Ciceronianus the White
There is much to recommend this. Except that it applies to every male from the age they become aware of their sex and learn to insist on a blue toothbrush not a pink one. Some of us are quite happy to say that gender roles and identities are
always toxic from the beginning, along with racial, and other socially imposed identities.
Thus I am a man, and therefore whatever I am is part of maleness and whatever I do is part of maleness, and there is nothing to conform to and nothing to perform. On this view, there is no achievement, no winning of the woman, or finding a place in the dominance hierarchy - I haven't had a fight for 58 years,
but ain't I a man? A gay man is a complete man and a straight man is also a complete man, and a transvestite is a complete man. A celibate monk and a gigolo are both complete men.
But masculinity confines, restricts, imposes, on all men a single image to which one must conform or face penalties - sometimes the death penalty.
But one must remember the source of this language is the political talk of women. And in practice, the emphasis will be exactly what is being presented by some here as the essence of masculinity - domination, aggression and violence, domestic abuse, and at the extreme, rape.