iPhone / iPad :
Open Settings.
Tap General.
Tap About.
Scroll down to the SIM or eSIM section.
Look for ICCID. (If multiple SIMs or eSIMs are installed, check the details for the correct line.)
Samsung :
Open Settings.
Tap About phone.
Select Status information.
Tap SIM card status.
Look for ICCID.
Google Pixel :
Open Settings.
Tap About phone.
Look for SIM status or SIM information.
Find the ICCID field.