There isn’t near the kind of cultural narrative about stepfathers that there is about stepmothers, especially in media for kids. Kids absorb ideas from the fairy tales they see and hear. Stepmoms have to deal with tropes from “Cinderella” to “My Stepmom is An Alien”. Kids will then carry those notions, amorphous and unexamined, into their new relationship. Kids usually don’t have the capacity to recognize those kind of prejudices in themselves. So now the new stepmom has to deal with the kid’s indignance at a fictional character. But aside from the Dursleys in Harry Potter, I’m hard pressed to recall a wicked stepfather.
Then there’s the puritanical thread, and I’m a dude so I don’t even know what else is lurking in our culture that wants to take a piece out of a stepmom for being the second lady in the family.
Not to reduce what a genuinely good dad has to do, step or otherwise. But if a dad manages to use words to explain something calmly, that’s enough to get kudos from strangers on the street. I don’t think the ladies have the benefit of the same uncomplicated expectations, so they need specialized guidance.
What exactly are you looking for in advice? How to deal with the ex and their branch? How to deal with specific behaviors from the kids? You’ll probably do better to search at the level of those topics than the role of stepdad in general.