Yes, you can.
Just click on the magnifying glass icon, then enter the contact name or number you're looking for in the search bar and press enter. If the name or number you're looking for doesn't come up in the search, there are two likely reasons:
- The conversation may have been closed, just select the Closed tab at the top of the inbox and perform the search again.f
- The most recent activity in the conversation was from more than 90 days ago, and because the inbox only displays 90 days of message history, the contact you're searching for won't come up in the search.