Canon R6 V has a
32.5MP Full frame (36 x 24 mm ) sized CMOS sensor and features Digic X processor. On the other hand, Leica SL3-S has a
24.0MP Full frame (36 x 24 mm ) sized BSI-CMOS sensor and features Maestro IV processor.
Canon R6 V's sensor provides 8.5MP more than Leica SL3-S's sensor, which gives a significant advantage in real life. You can print your images larger or crop more freely.
On the other hand, please keep in mind that Max sensor resolution is not the only determinant of resolving power. Factors such as the optical elements, low pass filter, pixel size and sensor technology also affects the final resolution of the captured image.
One other difference between these two cameras that is worth mentioning is that Leica SL3-S's sensor doesn't have an 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 R6 V and SL3-S sensor size comparison.
Sensor Size and Resolution Comparison image of Canon R6 V and Leica SL3-S Cameras
Canon R6 V and Leica SL3-S have the same sensor sizes so they will provide same level of control over the depth of field when used with same focal length and aperture. On the other hand, since Leica SL3-S has 42% larger pixel area (36.00µm 2 vs 25.26µm 2 ) compared to Canon R6 V, it has larger pixel area to collect light hence potential to have less noise in low light / High ISO images.
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
Canon R6 V
or the
Leica SL3-S ,
including hyperfocal distance.