Several third-party websites act as a facebook full link size profile picture viewer. These tools require only the URL of the profile you wish to investigate.
Have you tried this method? Let me know in the comments if the _o.jpg trick worked for you or if Facebook has patched it recently. facebook full link size profile picture viewer
If you prefer not to install third-party software, these manual tricks often work for public profiles: : Click on the user's profile photo to open it in a popup. Several third-party websites act as a facebook full
Here is the quickest way to become a full-size profile picture viewer using nothing but your browser’s address bar. Let me know in the comments if the _o
Once the image loads in your browser, it is the full link size. Right-click and select "Save image as." It will often be a .jpg or .png file significantly larger than the thumbnail.