You're looking for a guide on the Minecraft 1.12.2 Fullbright texture pack!
It is impossible to discuss Fullbright without addressing its controversial cousin: X-Ray packs. minecraft 1122 fullbright texture pack updated
Several "Fullbright" resource packs and methods are available for You're looking for a guide on the Minecraft 1
This is a client-side visual change. It does not give you a PvP advantage on anti-cheat servers (like Hypixel) because it doesn't remove shadows from the server's perspective—it only brightens your screen. However, it is a lifesaver for single-player and modded servers. minecraft 1122 fullbright texture pack updated
Follow this guide to ensure you get the updated version working correctly.