Fullbright Texture Pack 1.12.2 Link

If you want to make one from scratch for 1.12.2:

Advanced version: Use a gradient from white to light gray for slight shading, but pure white is the true fullbright. fullbright texture pack 1.12.2

A popular hybrid for 1.12.2. This pack combines the gamma hack with a "Clear Water" texture. Underwater visibility is drastically improved, making ocean exploration in modpacks like SevTech: Ages much easier. Best for: Ocean monument raiders and builders. If you want to make one from scratch for 1

While this article focuses on texture packs, Minecraft 1.12.2 has a famous backdoor that many veterans use instead of a texture pack. If you cannot find a reliable Fullbright pack, you can use the Option File Edit: Advanced version: Use a gradient from white to

This forces Minecraft to ignore the brightness cap entirely. It is actually more effective than most texture packs for 1.12.2. However, be warned: This makes the game incredibly bright. Looking at snow biomes will feel like staring at the sun.