Call of Duty: Modern Warfare II does support crossplay on PlayStation 4, PS5, Xbox One, Xbox Series X, and PC (via Steam and Battle).

On PS4, the base file size is only marginally different, at 35.490GB, but each individual pack takes up significantly more space than they do on the PS5. The first campaign pack is around 7GB, with the second taking up 11.598GB. Multiplayer takes up around 5.5GB, while co-op is just over 3GB.