Before copying any files, make sure you create a backup of your Textures and Terrain folders so you can return to normal sand and dust later.

in your Journey game folder, go to Data > Textures and copy the modded folders to make the sand black in every level and the credits, just like the Black Sand glitch on PS4.

Optional: go to Data > Terrain and copy those if you want an upgraded version of the Black Sand glitch. These edits will make it so the borders of objects and the dust in each level is black instead of their original colors. For example: in Pink Desert, the edges of war machines will blend into the black sand, instead of having the original pink edges. When you dropshoot, you will blend into the sand, instead of turning pink. When you kick up dust during a dropshoot, it will be black instead of pink.

If you want your Black Sand glitch on PC to be exactly the same as the PS4 version, copy the Textures only and do not copy the Terrain files.