The Call of Duty games are on the Gamecube, Xbox, PlayStation, PlayStation 2, PlayStation 3, PlayStation Vita, PlayStation 4, PlayStation 5, Xbox 360, Xbox One, Xbox Series X, Xbox Series S, PC, Nintendo Wii, Wii U, and the Nintendo DS.
Call of Duty: Modern Warfare II does support crossplay on PlayStation 4, PS5, Xbox One, Xbox Series X, and PC (via Steam and Battle). This means regardless of your platform, you'll be able to play with users on other systems or devices.