honestly there's nothing that's going to work for every kid but I've found just turning kid behavior back on them usually works pretty well. like if they say something about "girls are like this and boys are like that" be like why. why. why. why. exactly the way little kids do. they'll try to come up with an answer but usually after like five rounds of me asking why they'll eventually be like huh. idk.
in my case it definitely helps that I teach kids martial arts classes at a boxing gym with a lot of women. so little boys just factually cannot tell me that girls can't fight or aren't strong or something, because they're constantly surrounded by proof that isn't true. also rules are very different in a boxing gym so if a kid is being a little shit I'm allowed to pick them up and put them in upside down air jail. you probably can't do this in most contexts.
I think the biggest thing is that they need to see men and other boys listening to women. they're following the example that's been set for that. at home maybe their dad never listens to their mom, but when they show up at my class all the other boys are following my instructions. peer pressure is real and you can use it to your advantage. I make a point to tell the biggest buffest manliest dudes what to do in front of the little boys. now this works because those dudes already listen to me, but getting any dudes to follow your instructions could probably work.
the best punishment is the natural consequences of your behavior. if a kid isn't going to listen to me, he doesn't get to do class. this works because class is fun and he wants to kick stuff and hit people with noodles. kids want to have fun more than they want to misbehave. as long as listening to me is more fun than misbehaving, they'll listen.
because these boys are learning this behavior from their dads, the dads also tend to be the kind of tough strict emotionally distant parents that would yell at "girly" behavior or crying. even when I'm strict with the kids, I never yell, I obviously never hurt them, and I always listen. they want to yap at me about pokemon or youtubers. it can be tough when they're really sexist at the beginning but eventually they will show you something that their dad wouldn't approve of, whether they want a pink noodle or quietly mention they like a girly show. this is the part where you simultaneously act like it's no big deal while encouraging it. you need show it's completely normal for a boy to want or like that. if you can, bring up another boy or man they know who likes the same thing. I always show off my nails to the kids and bring over the guy who also paints his nails. you'll probably get "boys can do that?" comments and I usually just go "well he's a boy and he did it, so unless his hand falls off right now I think it's okay"
for me, it's always eventually gotten to a point where the boys realize that everyone else thinks it's normal to listen to women, and that if they want to have fun they need to listen too. they also realize that these people and these women are nicer and listen to them more than their dad does. they notice how all these nice people that make them happy talk to women very differently than their dad does. when those boys yelled at their dads for being rude to me, I made a point to thank them and say that they were right and their dads were rude.
encouraging the behavior you want to see is even more important than punishing the behavior you don't want to see. you can't tell kids what not to do without giving them something to replace the behavior with.
