Your question should really be about your camera expectations/requirements, and compatibility with the Operating System (not OBS Studio).
Discussions around specific webcams often have to do with multiple webcams from same vendor, and poorly written drivers, and non-USB standards compliant hardware (re-using IDs, etc)
Your iPhone camera is probably better than most webcams, but it depends on focus depth, lighting, etc as to what will work ok/best for you. Typically if the OS can see/use camera, so will OBS Studio. In your case, Apple makes things difficult with iOS (walled garden). So, yea, iPhone with MS Windows... not a great pairing.
As for webcams, beware those with fixed-focus (or really limited focus length) lens.
There are really good webcams (approach quality of lower-end interchangeable lens (ILC) cameras), but they cost more. so depends on your budget and requirements.
Your 'best' image quality is likely to come from a DSLR/mirrorless camera with clean HDMI out, and associated HDMI capture device... but it depends