To get "Fullbright" functionality in Minecraft 1.12.2 , you can either install a dedicated or manually adjust the game's gamma settings in the configuration files. Both methods allow you to see perfectly in dark caves and at night without torches. Method 1: Use a Fullbright Resource Pack
In essence: Caves look like sunny fields. Night looks like day. No more squinting. minecraft 1.12.2 fullbright texture pack
This is the easiest way to get fullbright without downloading anything. It forces the game's internal brightness beyond the standard "Moody" or "Bright" settings. Close Minecraft. To get "Fullbright" functionality in Minecraft 1