To add or edit your email you will do the following:
2a. ( iOS Version 14.1 updated iPhones ) - Mail - Accounts
2b. (iOS Versions before 14.1 update) - Passwords and Accounts
3. Locate your email under ACCOUNTS (if adding an account you will choose Add Account)
If you are adding an account to your iPhone
4a. Select Microsoft Exchange (O365 Accounts)
1. Add your email
2. Description (what will display for you under the mail app)
3. Choose to Sign In (if you have 2FA / authentication enabled you should get a prompt on your phone)
4. Once you approve the sign in, you will come back to the SETTINGS and finish up.
4b. Google (gmail accounts)
1. Sign into your google account.
2. If you have authentication setup youll get the code.
If you are editing an email account on your iPhone
4c. Choose the account you wish to edit
1. Edit the settings that need to be edited
5. Once the above steps are done, you will want to go to the mail app and verify that you see your account.