There's a separate inbox for emails where you're waiting for replies.
Find them in the "Follow Up" mailbox, and tap "Follow up" to compose additional follow-up messages.
iOS recognize these mails based on the content in your mail. (iOS 16 only)
Separate inbox waiting for replies
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Double-tap to make the text all caps
Double-tap the shift button to make the text all caps when you write
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5 Clever iPhone Features and Shortcuts
Unique iPhone tips including voice control scrolling, caps lock shortcut, and app locking with Face ID