To see all of the conversations you have with the phrase or word you look up on your iPhone 14 Plus:
- Open the Messages app.
- Swipe down on the list of conversations to reveal the search field.
- Type the phrase or word you want to find and tap Search.
- Ensure you have not enabled any filter as shown in the pic below...

Selecting All messages will show you all of the conversations you have that contain the phrase or word, regardless of how recent they are.
If you're still not seeing all of the conversations you expect to see, try the following:
- Make sure that you're searching for the phrase or word exactly as it appears in the conversations. For example, if you're searching for the phrase "dinner party," make sure to include the space between "dinner" and "party."
- Check your Messages settings to make sure that all of your conversations are being indexed. To do this, go to Settings > Messages > Search and make sure that the "Search Messages" toggle is turned on.
- Restart your iPhone.
If you're still having trouble, contact Apple Support for further assistance.