This Seeking Tech article compares Final Fantasy XII: The Zodiac Age with the PS4 Image Enhancement feature of the PS5 Pro enabled and disabled. The game originally runs at 1080p on PS4 or 1440p on PS4 Pro.
You can find the video comparison below:
There does not appear to be any noticeable difference with the game on the PS5 Pro with the PS4 Image Enhancement enabled or disabled. Unfortunately, the game still runs at a locked 30 fps.