Simply adjust and configure the gamma as you wish.

Important note, on 1.12.2 and 1.20.1(for strange reason), the gamma setting is not connected/related with the default brightness slider. But you still have the main GUI adjustment (keybinds are configurable)

Gamma adjustment (Toggle with G)

For 1.21.1, default brightness slider works too

Adding this mod in a modpack and publishing it to curseforge is highly appreciated, thanks!