: If you don't want to use a resource pack or Optifine, you can manually set or higher in your options.txt file located in the .minecraft Step-by-Step Installation Download the Pack : Visit a reputable site like FullBright on CurseForge

Version 1.12.2 is actually one of the best versions for Fullbright packs because Mojang hadn’t yet implemented the strict lighting overrides found in later versions (1.14+). Many classic Fullbright packs were designed specifically for 1.12.2 and remain stable.

If using OptiFine 1.12.2, Fullbright still works. Some OptiFine internal settings (like “Dynamic Lights”) are unrelated and won’t conflict.