Select the three dots at the end of the search bar and then choose Take a Screenshot. You can scroll beyond what is visible to highlight multiple screens. When done, select Download at the bottom of the select window.

Arghh that is the answer i see everywhere but there is no ‘take a screenshot’ option? Can you please post an image of this from IOS? It is on MacOS but neither my iPhones nor iPads have the option....

This is what i see

While this function is available on iOS, I don’t see any way to capture a screenshot of an entire page in Firefox (only the viewable portion of that page).