Conflict: Desert Storm II does not natively support widescreen resolutions. If you go into the in-game options, you will likely see resolutions topping out at standard definition. The game engine is hardcoded to assume a square screen.
This is the safest, easiest method that modifies the game's executable to accept custom resolutions and FOV. conflict desert storm 2 widescreen fix
If the game won't save your changes, ensure you are running the CDS II.exe with administrator privileges. Essential Performance Fixes Conflict: Desert Storm II does not natively support