I have an alternative resource pack with a 128x resolution, and the items/blocks look very blurry on the inventory and when they're distant. I saw another user reported this two years ago, and the solution was editing the terrain_textures.json file. But the details of what changes need to be made in order to fix the issue were not specified. 

I'd like to be able to fix the issue as its very annoying, and I got the texture directly from the marketplace (PureBDCraft). I attached some screenshots, just in case.

Thank you for your assistance!