Not every email needs to be sent right away. In iOS 16, the Mail app now gives you the ability to schedule emails to be sent at a specific time.
Send Later with Mail
Open the Mail app and create a new email draft.
After writing your email, press and hold the send button (blue up arrow).
Select one of the preset times or pick Send Later to use a custom time.
Tap Done to finish
On the main Mail app screen under your email account list, you'll see all of your emails set to Send Later.