The iPhone 6 and iPhone 6 Plus will be released soon. Japanese media have also tested their graphics performance and listed a summary of GFXBench's test results.
As can be seen from the figure, in the 1080P Offscreen test (regardless of device resolution), the iPhone 6 Plus scored 2503, which is a big departure from previous iOS devices, and also exceeds the score of Snapdragon 805. It can be seen that the GPU capability of the A8 is quite strong, and I believe there is no problem with the resolution of the iPhone 6 Plus.