Minecraft: Bedrock Edition v1.21.100 or higher supports activating custom shaders through resource packs.

As of right now, Minecraft can load shader definitions through the resource pack, but not the shader files themselves.

i.e. Minecraft loads the materials.index.json file from a resource pack, but not the .material.bin files themselves.

This .mcpack serves a dual-purpose of acting as a ZIP archive as well as a resource pack.

Step 1. Create a shaders directory

Create a new directory named shaders in the game installation's Minecraft Preview for Windows\Content directory.

Step 2. Extract the .mcpack

Extract the contents of the downloaded .mcpack into the newly created shaders directory. You can use any ZIP tool to extract the contents, or rename the .mcpack to .zip and extract through Windows Explorer. (Change it back to .mcpack after extracting.)

Step 3. Install the .mcpack

Double-click the .mcpack file to launch Minecraft and install the resource pack. Add it to your global resource packs. Changing presets requires restarting the game.

Ensure RTX is ON

If the Ray-Traced Graphics settings are greyed out, you can enable them through the options.txt file in your com.mojang directory.

Add the following line to the options.txt file to activate ray tracing:

graphics_mode:3

(Minecraft must be restarted if the file is modified while the game is running.)