Activision frequently runs "Free Access" periods for Modern Warfare II . These are limited-time events where the Multiplayer component is unlocked for everyone, regardless of whether they own the game.
Since Microsoft acquired Activision Blizzard, MW2 has been integrated into the Game Pass library. how to play call of duty modern warfare 2 for free
I can give you the or optimization settings for your specific setup. Activision frequently runs "Free Access" periods for Modern