Turn off "Fast Render" in OptiFine settings.
If you use OptiFine, configure these settings under : Connected Textures: Fancy Custom Colors: On Natural Textures: Off Custom Entity Models: On Random Entities: On Alternate Blocks: On (under Detail Settings) 3. Recommended Shaders patrix-1.16-128x-basic.zip
Because this is the "Basic" version, the pack relies less on complex shader lighting. You can technically run it with just OptiFine. However, to get the "hyper-realistic" look associated with Patrix, pairing patrix-1.16-128x-basic.zip with a light shader pack like BSL or Complementary Shaders is the ideal setup. Turn off "Fast Render" in OptiFine settings
You are using the wrong Minecraft version. patrix-1.16-128x-basic.zip