The original Warzone was complex enough on its own, and its sequel continues that trend, with new mechanics that will likely confuse even the most dedicated players at least at first. While Warzone 2.0 is fundamentally very similar to its predecessor, it comes with a host of changes you should be aware of.
From the most minor changes, such as the graphics and user interface, to the most major changes, like the map and the in-game engine, this is a totally new game. It isn't just an expansion, and it isn't a follow-on like Call of Duty Warzone Caldera was, it's a completely new and original game.