World scale is related to IPD (Interpupillary Distance) not focusing or camera distance.
First - you should set the physical IPD in your headset according to your actual IPD. If the optics of your headset are set wrong, your eyes will be not in sweet spot (centre) of each lens and the sharpness/clarity will suffer.
Second - the perceived scale of the world depends on the IPD which is assumed by the sim. If your eyes are further aways from each other vs the distance assumed by the sim, you will see the world as elephant looking at the world projected for the mouse. It’s very subjective, a perceptual thing. So if you have the impression that your cockpit or your virtual seat is too small, you can “increase” the virtual world size by changing the IPD in the sim.
This has nothing to do however, with the image sharpness or clarity, as long as your physical IPD is set correctly in the physical headset.