Xbox One has a system features, the excellent co-pilot share controls mode and adaptive controller support for all games. Some are system only, some work in games (invert colours and button mapping). PlayStation 4 has a range of accessibility settings. Lots of accessibility software can be used with PC games, from voice recognition to input device emulators. Some, like colour correction, work with games. Windows has extensive accessibility features.
In addition to the accessibility features provided in the game, you can also use system-wide accessibility settings:
