This guide will give you all the information you need to better understand the featured feature of your iPhone. You can use the information in this guide to determine what the emphasis feature does and how you can use it yourself.
What does it mean when iPhone says emphasized? Know everything
The highlighted message simply means that the person who has seen your message has reacted to it by using the double exclamation mark emoji. This is simply meant to indicate that the user has seen the message and reacted to it with excitement.
This is a built-in feature that all iPhones have. You don't need to do anything special to trigger this message, as it's simply an emoji that indicates interest or excitement in response to a message you've sent.
Once your message has been highlighted by another user, !! Icons appear next to the message to indicate the reaction. You can use this as the main indicator that someone has highlighted a message you've sent.