You could make a 4K image with your iPhone, but it will not nearly be anything like what this video shows. Please do look at the video. I thought it was pretty amazing the level of detail available and I don't even have a proper 4K screen (2560x1600), it is much better than any other video that attempted to do something like this and it is more about the LRO mission and the data it generated than about the output resolution of the video, with the note that generating output at a higher resolution would have been pointless so they did the best they could.