Both Panasonic S1 and Nikon Z6 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 Panasonic S1'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 S1 and Z6 sensor size comparison.
Sensor Size and Resolution Comparison image of Panasonic S1 and Nikon Z6 Cameras
Panasonic S1 and Nikon Z6 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.
DxOMark Sensor Scores
At Camera Decision, we also look at Dxo Mark sensors when available as we think it is a good indicator of image quality.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Panasonic S1
95
25.2 bits
14.5 Evs
3333 ISO
Nikon Z6
95
25.3 bits
14.3 Evs
3299 ISO
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 S1
or the
Nikon Z6 ,
including hyperfocal distance.