Downloading unofficial ISO files from third-party sites carries significant risks: Security Threats:

The specific file described as does not exist in a legitimate form.

If you want something closer to MK9 (the reboot before MK11), you need (PS2 emulator), not PPSSPP. The file size is ~4GB.

Which of these would you like?

Searching for a " Mortal Kombat 11 PPSSPP ISO Arquivo Download 300MB" typically refers to or re-skinned versions of older games, as a native version of Mortal Kombat 11 was never released for the PlayStation Portable (PSP). The Reality of "MK11" on PPSSPP