speak about typically feminine traits highly. Use words like assertive over bossy, refrain from using typically feminine traits as 'bad' (i.e. oh my goodness you're so emotional today vs I can see you're having a hard time/some big feelings right now) ensure boys have a high value for women and ensure that the separation between ability is not emphasized (saying things like toys and dress up is for everyone or colours do not have a gender)
talk about it early and often as age appropriate levels, use intentional language and reflect before you speak or make comments about children's activities or preferences. Talk about women how society talks about men (strong, leaders, creators, competent, social, capable, indipendent)
For me it starts at home — making sure my kids see me valuing feminine things, not apologizing for them. If I'm excited about a sparkly decoration or a pink sweater, I say so. If my son wants to paint his nails, we do it together. These small things add up.
I've started gently redirecting when I hear kids dismiss something as 'girly.' Instead of letting it pass, I'll say something like 'I actually think that's really cool — why do you think people say it's only for girls?' It opens a conversation without shaming the child.
I think we start by not laughing — not at the 'man in a dress' joke, not at the boy who cries. Stopping our own passive participation in the mockery is the first step. Then we can actively model: I tell my son I love how gentle he is. I say it in front of his friends.
We can talk explicitly with kids about why some things get called 'for girls' — and how that's a put-down, not a description. When children understand that femininity is being dismissed, they can start to push back on it themselves, rather than absorbing the message uncritically.