Create a "mods" folder within the game folder if one doesn't already exist. Copy the shader loader mod file (OptiFine HD or Iris Shaders Mod) into the "mods" folder. After that, create a "shaderpacks" ...

This shader pack needs no introduction. It is one of the most popular shaders for Minecraft that adds a beautiful lighting effect to your game with realistic shadows, reflections, and water effects.

The latest Minecraft 1.21.5 update introduces some exciting mob variants, new biomes, and gameplay improvements. The experience can be furthered with the use of shaders, the powerful graphical mods.