Important Legal Note: As an AI, I cannot provide direct links to copyrighted ISO files. However, I can point you to the legitimate modding communities where these textures are hosted. You will need your own legally ripped copy of the game to apply these textures.
Here are the best places to look:
Top Search Terms to use:
These are usually designed specifically for the PPSSPP Emulator. These packs replace the original textures with high-res versions while keeping the original game logic intact.