Ok. My boys are 13 and 9 so we've not got through the teenage years yet, so take it all with a pinch of salt.
First, there's plenty of research to show that we all unconsciously socialise our kids into gender roles, to a greater or lesser extent, pretty much from the moment we know their sex. And the more people they spend time with, the stronger that association is likely to be. So to a degree it's inescapable and you have to work within the system we've got.
My boys aren't perfect. They scrap and scuffle, they wind each other up mercilessly but that's siblings.
We have never, ever accepted any "boys will be boys" bullshit. Zero tolerance, we challenged it every time from a young age. We worked hard to make sure that we had really clear boundaries in place and enforced them pretty ruthlessly.
At the same time we didn't demonise "boy things" in favour of girl things or vice versa. DS2 got a huge amount of joy from his dolls house for years - he's a storyteller and it was perfect for him. But he's also nuts about hot wheels and even now he and the Big Cool Teenager can happily spend hours in complicated car racing tournaments. DS1 is in the county basketball playoffs but he's also a shit hot baker and likes to experiment with flavours.
And I think it's important to be open and recognise that from their perspective there will be times that it feels like the odds get stacked against them. The one day a week where it's "girls only" in the MUGA at school makes perfect sense from a societal or even community-wide perspective, but if you're 7 and there's not an equivalent for boys, then it hits differently and it needs both acknowledgement and explanation while still supporting the principle.
This is something that we're encountering in a more serious way with DS1 as he gets exposed more to the "straight white men" discourse - we've had some serious chats about the nature of meritocracy, some of the structural discrimination people experience but also the shortfalls of that sort of discourse if it's applied too simplistically - particularly around how class plays into it. It's actually made more difficult because we've got a very equal household and explaining the inequalities that almost certainly exist in some of his mates' homes has been difficult for him to get his head around.
The most important thing is role modelling. It's not an accident that the kids have a father who does his share (and probably more than his share) of housework and childcare. We shared the parental leave. We both work a compressed week. We cook pretty equally. He does more of the laundry, I'm better at DIY. DS1 wants to go on an expensive school trip, he earns part of the cost through taking on additional chores.
I don't think there's a magic formula and I'm dreading the next ten years, especially as DS2 is a much trickier character than DS1. But so far openness, talking and having clear standards has worked for us.