You need to underatnd how games run to begin with. In simple terms
It takes a certain amount of time for each frame to be rendered. Both the CPU and GPU needs to finish their tasks which results in a new frame.
Even if you make a GPU 10 times more powerful but it still take the CPU the same amount of time to finish its tasks as it did before, then the 10xGPU will still give you the same maximum framerate.
In other words, having a better GPU isn't enough to have higher/double framerates if the CPU remains the same. Yes there is a slight up clock to the CPU, but unless a game was already internally running @ 45-55fps but locked to 30fps on the PS4, the PS4pro wouldn't suddenly make that game start running at 60fps.