Once the shader pack file is inside your Minecraft shaderpacks folder and you are running a shader loader such as Iris or OptiFine, you can switch it on directly from the pause menu without restarting the game.
Activating the Pack
1. Load into a world or stay on the main title screen and open Options.
2. Click Video Settings, then open the Shaders or Shader Packs menu provided by your shader loader.
3. Select MC Modification Shaders from the pack list and click Done or Apply to reload the renderer.
4. Return to your world and look toward the sky or nearby blocks to confirm that soft shadows and sunbeams are active.
Adjusting Pack Options
If you want to fine-tune how the world looks on your screen, reopen the Shaders menu and click the shader pack settings button while MC Modification Shaders is selected. From there, browse the pack's categories to tweak shadow softness, water reflections, or sky effects to match your preference, then apply your changes to see them update immediately in your world.