Depending on your setup, the process for launching the ISO varies:
Tools to transfer save files between memory cards and external storage. How to Use the Xploder PS2 ISO in 2021 xploder ps2 iso 2021
When prompted to "Start Game," use the emulator's menu to swap the ISO for your actual game disc image and press start. On Original Hardware (Modded) Depending on your setup, the process for launching
The most advanced version commonly used in 2021 for the widest game compatibility. THE BEST PS2 emulator in 2021 - PCSX2 Setup Guide for NOOBS Depending on your setup