Agreed on Atalanta, but like I said I think that's unusual for a back three.
In teams that press less you still want CBs stepping up, but it's more often the wide CBs that do that most of the time. That way at least you have the central CB covering the route to goal somewhat if someone gets in behind the CB pushing up.
As the video I linked highlighted Romero did similar things for Argentina, though perhaps not as far as often (I don't know, only based on that video based on just a few games it's difficult to say). Argentina and tactics tough, and Argentinian defending, not always the standard approach.
Not really trying to argue one way or the other. Just found the video an interesting analysis and take on Romero. Been very good playing that rather particular role and it seems to be not just tactics, but also a part of his style.
How we will adjust, how we will adjust, I don't know. He seems to have more in his locker than that, be able to play in different ways, but I assume we've bought him in part because of that aggressive style he likes and his chances of hitting the ground running will probably increase if our system allows him to play an aggressive style.