Classically, any SLR 6x6 and smaller was considered to be better suited for field work, and cameras 6x7 and larger were largely relegated to studio work. A few cameras like the Pentax 67 were in the field a lot, but generally those who carried Mamiya RB and RZ into the field were more likely the hair shirt wearing afficianados. Many relatively light field folding 4x5 camera were taken out as well, but the fundamental design was implied in the name 'field' 4x5. Yes, you have 4x5 and 8x10 cameras in the field, and sometimes they are monorail designs and not field folding designs, and again these are the hair shirt wearing purists.
(I exaggerate the characterization of the large or heavy camera field user, for levity!)
In the interest of IQ, bigger is better, since larger captured image results in lesser magnifications to achieve a given large print size. So the detail resolution generally is better, as is the tonality benefit.