Search Limitations Before you start your search, know that you can only search through text messages saved as conversations within the Messages app on your iPhone.
How to Search for Text Messages with the Messages App The best way to search through your text message history is using the Messages app.
If you are in a Conversation view, press the back arrow until you are on the main “Messages” screen.
How to Search Your Text Messages with Spotlight You can also search through your text message history using Spotlight Search.
If Messages do not appear on your Spotlight search results, open Settings and navigate to “Siri Search,” then scroll down to the Messages app in the list and tap on it.