Both Nikon D750 and Leica M10-D have Full frame sized 24.0 MP resolution sensors so sensor size and resolution is not a differentiator between these two cameras.
Below you can see the D750 and M10-D sensor size comparison.
Sensor Size and Resolution Comparison image of Nikon D750 and Leica M10-D Cameras
Nikon D750 and Leica M10-D 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
Both Nikon D750 and Leica M10-D sensors have been tested by DxoMark. DxoMark scores camera sensors for color depth (DXO Portrait), dynamic range (DXO Landscape) and low-light sensitivity (DXO Sports), and also gives them an overall score. Of the two cameras that we are comparing, D750 has scored 93, 7 points higher than M10-D.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Nikon D750
93
24.8 bits
14.5 Evs
2956 ISO
Leica M10-D
86
24.4 bits
13.3 Evs
2133 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
Nikon D750
or the
Leica M10-D ,
including hyperfocal distance.