If the image exists in that size and is public, you will see a 720x720 version. If not, you will see an error.
Downloading apps that promise "HD viewers" or "private photo unlockers" often leads to malware or intrusive adware being installed on your device. Summary Table: HD Viewing vs. Privacy Official Facebook Capability Third-Party App Claim HD Resolution Available if the user uploaded in HD Often just scales the thumbnail (blurry) View Private Photos Blocked by "Locked Profile" settings Usually a scam or phishing attempt Viewer Tracking Not possible; Facebook doesn't allow it Fake; used to lure users into clicking ads optimize your own profile picture facebook+profile+picture+viewer+hd+hot
The Illusion of Access: Why “HD Hot” Profile Picture Viewers Violate Privacy If the image exists in that size and