Rockstar Games released the following on PSP:

$$ \textPerformance \propto \frac\textProcessor Speed \times \textRAM\textStorage Capacity $$

: GTA 5 requires over 100 GB of space. Even a "highly compressed" version would be far too large for a PSP emulator's architecture.

If you're concerned about the legitimacy or safety of downloading a PPSSPP ISO file, you may consider alternative options:

Grand Theft Auto V (GTA 5) is an iconic game that has captured the hearts of gamers worldwide. While it's originally designed for console and PC platforms, many Android users want to experience the thrill of GTA 5 on their mobile devices. One popular method to run GTA 5 on Android is by using the PPSSPP emulator, which can run PSP games but can also be used for other platforms with some adjustments.