Uhhh not sure. The "Arena" in DOS2 was technically PvP because you could fight your party members. So there may be some sort of other "casual" way to fight your friends.
But there's themes of betrayal, and if you've already beaten DOS2 with more than one party member, then you'll know that (Big spoiler if you haven't finished the game) there's the first fight for Divinity where you're "against" your party members and then the second possible fight where you are once again against your party members and you even kind of pick "sides" depending on what everyone chooses.
So long story short, there might be some parts of the story (if "betrayal" is to be interpreted literally) that could involve you fighting party members. And both recreational PvP and story PvP would both count as online PvP I guess. Swen and the Steam description hint at betrayal so it's really not out of the question that you could fight one another.
Also if you watched today's stream until the end, Swen talks about how his character could have chosen to (Early game choice) bite one of the fellow party members and further chosen to drink all or their blood or leave them some. Although that's pretty early, I wouldn't be surprised if that could lead to a fight, even if not a "to the death" fight.