Both Leica SL3-S and Nikon Z6 III have Full frame sized 24.0 MP resolution sensors so sensor size and resolution is not a differentiator between these two cameras.
Another difference between these two cameras is that Leica SL3-S'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 SL3-S and Z6 Mark III sensor size comparison.
Sensor Size and Resolution Comparison image of Leica SL3-S and Nikon Z6 III Cameras
Leica SL3-S and Nikon Z6 III 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
Leica SL3-S
or the
Nikon Z6 III ,
including hyperfocal distance.
