From everything we know about the game so far, Code Vein II seems far-divorced from the original world of the Gaol of the Mists that Code Vein takes place in. If the sequel were to be directly implicated, it could be troublesome in the future to distinguish the posts when so much about the games is visually distinctive and where it isn't a clear straight-path-continuation of the first game.
That being said, since we've now reached the point of discussing a series tag, what's on my mind here is if there's any room to consider adding this to God Eater. Code Vein is a spinoff of God Eater and specifically takes place in that world at the time of an initial Aragami invasion where the technology and strategies are more primitive in nature. To put it another way: NieR:Automata belongs to NieR (Series) which lives beside NieR, and that spinoff relationship is about as relevant as the one here, but it's not as far removed as NieR:Automata is from Drag-On Dragoon.