One effective method is to use a reverse image search tool, such as Google Images or TinEye. These services allow you to upload an image or provide a URL, and they will then search the internet to find other instances of that image. This can potentially lead you to the original source of the photo, which may contain information about the person depicted. By examining the search results, you may be able to find social media profiles, news articles, or other web pages that identify the individual.
Another option is to use a facial recognition search engine, like PimEyes. These specialized tools analyze the facial features in an image and compare them to their database of faces, potentially matching the photo to an online profile or other identifying information. This can be a powerful way to locate someone, but it's important to be aware of the privacy implications and to use such services ethically and responsibly.