Recover Email
How do I recover my email on my iPhone 12 after deleting the app
Try this: Use App Library to search Mail app, see this Apple article:
Organize the Home Screen and App Library on your iPhone
Organize the Home Screen and App Library on your iPhone - Apple Support
If you have find the Mail app, tap & hold on the app, then drag to the Home screen & drop it.
Hopefully the emails will come back too.