The dimensions 760x1226 align with a portrait aspect ratio (roughly 9:14.5) often seen in screen captures or specific UI assets on older or smaller iPhone models like the iPhone 8 or iPhone SE .

Select to generate a web URL for sharing. Paste that link into a message or email. Share content in Messages on iPhone - Apple Support

While not a standard global resolution for every app, this specific dimension (760x1226) is closely related to how generated link previews and shared media during that period:

If you are trying to replicate or find this "sharing piece," the standard method in iOS 14/15 (the 2021 versions) was: or Safari. Tap the Share button (the square with an up arrow).