Viewing a locked Facebook profile picture in full size is officially restricted to only the user's friends
It is essential to understand the risks associated with third-party viewers:
: Most of the "About" section is hidden from public view. Online Profile Picture Viewer Tools
Therefore, any website claiming to "view" the locked image would have to either:
Searching for "facebook locked profile picture viewer online top" yields dozens of websites promising instant results. They claim to use exploits, API loopholes, or database leaks to reveal the full, high-resolution locked image.