How to know if my iOS is corrupted and how to fix it

What behavior is the iPhone exhibiting that makes you think the iOS is corrupted?

Have you performed a Forced Restart....(which is not the same as a factory reset)?

Force restart iPhone - Apple Support

Even in the highly unlikely event that the software is at fault, there would be no way to avoid a factory reset in order to install new software.

Depends on what you are experiencing? If you have a corrupted iOS install, which is not likely but has been seen when an update failed, then you will need a computer to perform a Factory Reset to restore the OS. That is the only way to resolve that problem.

For a corrupted cache file, then a Force Restart will clear those caches to have them rebuilt again.

• Press and release Volume Up
• Press and release Volume Down
• Press and HOLD side button until the Apple logo appears. It may take up to 15 seconds while holding the side button before you see the Apple logo and you have to ignore anything else you see on the screen during that time. If the Apple logo does not appear then try again as it may take a couple of attempts to get the speed and sequence of the key presses correct.

Depends on what the actual issue is. “Corrupt iOS” is a meaningless term.

You did not answer the first question that we asked:

What behavior is the iPhone exhibiting that makes you think the iOS is corrupted?