You get both the Enhanced and Legacy Version added to your Steam Library of Games. The Enhanced version is a port of the game with all of the graphical improvements featured in the PS5/XS ports, some PC-exclusive graphics options and full support for PS5 controllers and their haptics/triggers.
If you already have the Legacy version, you can merge your character from the Legacy version over to the Enhanced version. That way, you can delete the Legacy Version and just play on the enhanced version, which will also save you some storage; despite the fact that the Enhanced Version is a graphical upgrade over the Legacy version, it takes up 20gb less storage than the Legacy Version.
The Legacy and Enhanced versions are considered separate games, so even if you port over your save file to the enhanced version and want to go back to the legacy version, you still can.
The only downside that the Enhanced version has is the lack of text chat.
I tried it on PC and PS5. It's so much better on PC. Not sure why. Just more responsive and easier to drive.