A command-line tool that lets you change gamma in GNOME and Cinnamon (with Wayland). You can also adjust contrast and brightness. It works by creating a color profile with the VCGT table, so that changes are persistent and don't interfere with other settings like night light.

Load 'vcgt'-tag of ICC profiles to X-server and MS-Windows. Works on calibration stage, which can be a precondition for display ICC color conversions.

ICC Examin colour profile, CGATS measurement, VRML gamut and ncl2 viewer