Couldn’t find my mail in settings

Tap the search for App Library and see if you can find Mail that way. If not, then you can download it again from the App Store. This is the one you want. In the App Store search "Mail Apple". You should be able to download it again no problem. Then go from there.

Employer provided devices can be managed by software and can restrict a number of things on the devices. They can also put a profile on the device. Screen Time controls restrictions on the device and you may have some turned on, or if you are a minor, your parents could have added restrictions. Not knowing anything about you, I need to provide for either situation.

You cannot delete in Setting, but did you possibly delete the Mail icon on your home page? If so, swipe your home screens all the way to the left until you get to the App Library. Find the Mail icon, the press and hold until it starts to wiggle and drag it to a home page. After you do that, restart the iPhone and see if mail reappears in Settings.

Is this a work managed phone, or do you have any restrictions turned on in Screen Time?

Mail is separate and should be listed directly under Passwords. What version of iOS do you have on your iPhone.

You're welcome. Glad you got it all sorted out.