I don’t see add account in email set up

1. Go to Settings > Mail, then tap Accounts.
2. Tap Add Account, tap Other, then tap Add Mail Account.
3. Enter your name, email address, password, and a description for your account.
4. Tap Next. Mail will try to find the email settings and finish your account setup.

Try this:

Settings > Screen Time > Content & Privacy Restrictions > Account Changes = Make sure you have this marked allow, then see if you can add your account.

https://support.apple.com/en-gb/HT201320