If you're playing Hogwarts Legacy on a base PS4, you'll be treated to a 900p resolution at 30 frames-per-second, but unlocking it sees you reach highs of 50fps. On the upgraded PS4 Pro, it's a 1080p resolution at the same 30fps. It's possible to achieve 60fps indoors, though, if you unlock the framerate. Going outside caps the frame rate at a high of 45. Compared to the five-second loads on PS5, the PS4 and PS4 Pro take about 40 seconds to get through load screens.
As for the visuals, you're obviously going to lose some quality across its overall graphical nature, draw distance, and lighting, but the results on PS4 really aren't that far off what's achieved on PS5. On launch day, at least, this looks to be a robust port that PS4 owners can happily enjoy.