Nikon D7200 has a
24.0MP APS-C (23.5 x 15.6 mm ) sized CMOS sensor and features Expeed 4 processor. On the other hand, Pentax K-3 III Monochrome has a
26.0MP APS-C (23 x 15.5 mm ) sized CMOS sensor and features PRIME V processor.
Another similarity between these two cameras is that both Pentax K-3 III Monochrome and Nikon D7200 sensors lack anti-alias (Low-Pass) filters. Removing anti-alias filter increases the sharpness and level of detail but at the same time, it increases the chance of moiré occurring in certain scenes.
Below you can see the D7200 and K-3 III Monochrome sensor size comparison.
Nikon D7200 and Pentax K-3 III Monochrome have almost the same sensor size, so neither of them has any significant advantage over the other in terms of providing control over depth of field when used with the same focal length and aperture.