ranged
is is the quality much better than default camera app?
Quality in relation to what? To answer that seriously, you would have to define what exactly is important to you.
There are some features the Pixel Camera has that the GrapheneOS Camera simply does not (yet) have: RAW support, astrophotography, motion photos, frequent faces, Google Lens, H.265 for video, 4K 60fps, to name a few.
On the other hand, GrapheneOS Camera scores in other areas, such as its focus on security and privacy, automatic removal of metadata, beeing able to use on a degoogled profile etc.
Image look is very subjective, as you have probably already noticed from the previous posts - there is no better or worse.
If I were you, I would simply try out different camera apps and compare results.
What's great is that you don't even have to decide - just get the best of both worlds: I personally mostly use GrapheneOS camera because I really enjoy the natural look. I switch to Pixel Camera where I think it's stronger: for me that's low-light shots and videos (especially motion-stabilized).