Have you tried Google Image search?

Facebook profile photos are public. If they have used the photo relatively recently a reverse image search may be helpful.

From Google Image Search, click the camera icon in the search bar ("search by image"), then choose the option to upload an image. (If you have a modern browser, you can also drag-and-drop an image file.)

Google will then use the image to find other images that either match exactly or come close.

There isn't a way within Facebook to use reverse image searches.

Have you tried Google Image search?

Facebook profile photos are public (for discoverable accounts). If they have used the photo relatively recently a reverse image search may be helpful.

From Google Image Search, click the camera icon in the search bar ("search by image"), then choose the option to upload an image. (If you have a modern browser, you can also drag-and-drop an image file.)

Google will then use the image to find other images that either match exactly or come close.

There isn't a way within Facebook to use reverse image searches.