If I want any more detail I zoom in on my photos and capture them at full zoom using the Share function, then I stitch them together in Photoshop.
Because GT7 outputs the photos at a resolution higher than 4K zooming in at the capture stage means you don't lose any quality, but if you capture without zooming in the PlayStation just captures whatever is on the screen at 4K. The resulting images are enormous - landscape images are around 7660x4230 rather than 3840x2160.
Portrait photos are even better using this method because the PlayStation Share function saves them as a small portrait photo in the middle of a 4K landscape image which is super frustrating.
The difference is most clearly demonstrated when adjusting both images to the same scale: