One specific file that continues to circulate among legacy version enthusiasts is:

This article breaks down what this file is, why the version numbers matter, and what kind of hardware you need to run it. Created by the artist known as Patr , the Patrix resource pack is designed to push Minecraft’s vanilla renderer to its absolute limit. Unlike simple texture replacers, Patrix uses advanced PBR (Physically Based Rendering) maps. This means textures react to light realistically—water becomes specular, stone looks rough, and metals actually shine.

If you are still running a 1.16.5 modded server or single-player world, this file remains the gold standard for photorealism. Disclaimer: Patrix is a paid resource pack (typically available via Patreon subscription). Always ensure you download the file from the official creator to support the artist and avoid malware.