Modern games typically don't change the screen resolution at all. If there is a resolution setting then it usually is just for the internal render resolution and the final pass will scale that up to the native resolution of the display. Changing the screen resolution only made sense with CRTs where the display is actually capable of different resolutions unlike LCD displays where there is only one native resolution and non-native resolution needs to be resampled (either by the display, the GPU or the game).