At the risk of coming across as argumentative - I can't reconcile the idea that every group except boys benefit from positive role models that help young people see their potential. I've known too many people who've benefitted from seeing POC or genderqueer people represented positively to believe otherwise, and I've seen it in my nieces when they find out that women are professionals in a field that interests them and they don't have to give it up because "it's a boy job".
Breaking down unhealthy gender stereotypes is an important job we all have to pitch in with, but
Young men do not need a vision of positive masculinity
feels like ceding all interpretations of masculinity to those who promote the kind of Gender Equity Reactionary Masculinity that came about in the later part of the 19th century which we now know as toxic masculinity. (Seriously though, it's behaviors and attitudes that have been promoted for barely over a century that eschewed actual traditionally masculine things like flower arranging, social sensitivity, and generally not being boorish.) If we're not willing or able to define positive masculinity for the next generations, we're likely to see more instances of the negative variety while possessing fewer tools to help offramp people from toxic behaviors to prosocial ones.
I mean, I'm a cis het white guy who enjoys wearing clothes that are cut for women. I do flower arrangements, and whenever I'm gardening somewhere public hand cut flowers to little girls and little boys and children who might not self identify along that paradigm. I wear flowers in my hair, or weave them into my hats. I am unafraid to use my dude voice or stature/build in defense of others. I will tell you I'm living my best life as a disney princess when I'm carrying baby animals around. All of these things help to define my masculinity rather than dilute it, and that's not to say that others might do the same things and have it reinforce their identity as feminine, or androgynous, or however they identify.