Both Panasonic GH5 and Olympus E-M1X have Four Thirds sized 20.0 MP resolution sensors so sensor size and resolution is not a differentiator between these two cameras.
Another difference between these two cameras is that Panasonic GH5's sensor lacks anti-alias (Low-Pass) filter. 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 GH5 and E-M1X sensor size comparison.
Sensor Size and Resolution Comparison image of Panasonic GH5 and Olympus E-M1X Cameras
Panasonic GH5 and Olympus E-M1X 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.
Sensor size sets the circle of confusion, so it drives how much depth of field each
of these bodies gives you at a given aperture. You can calculate it exactly for the
Panasonic GH5
or the
Olympus E-M1X ,
including hyperfocal distance.
