Open PPSSPP and right-click (or long-press) on God of War: Chains of Olympus .

The original PSP assets are low-resolution for a reason. Kratos’ skin texture, the marble floors of the Temple of Helios, and the fiery chains of Prometheus are all stored in tiny .GIM files (the PSP’s native image format). When the PPSSPP emulator renders these at 4x or 5x internal resolution, the polygons become smooth, but the painted details on those polygons remain pixelated and blurry.

The God of War: Chains of Olympus HD Texture Pack is typically made available through digital distribution channels such as the PlayStation Store. It's designed for players who own the original game on PlayStation Portable (PSP) or for those who have the game through backward compatibility on newer PlayStation consoles. The pack may be offered as a free update for existing owners, reflecting Sony's effort to support and enhance their back catalog.

Here's a more detailed analysis of the HD Texture Pack: