Starting from iOS 16 Software Version, you can
an iMessage after it is sent.
In a iMessage Conversation to Edit an iMessage, touch and hold a message untill the menu appears
Tap on Edit
You can make edit or even re-edit the entire message
Once edit is done, just tap on the check-mark at the right of the message
You can edit an message within 15 minutes after sending the original message
And the same message can be edited upto five times
You and recipient can view the edit history, if you both using iOS 16
Just tap edited below the message, to view what changes were made
Tap hide edits to return to the conversation
UNSEND an iMessage
Need to unsend an iMessage, you can make a message disappear within 2 minutes of sending it, as long as the receipient is also using iOS 16, the message will disappear for them too.
Just touch and hold the message untill the menu appears
And tap Undo Send