Nikon Z8 has a
46.0MP Full frame (35.9 x 23.9 mm ) sized Stacked CMOS sensor and features Expeed 7 processor. On the other hand, Canon R5 II has a
45.0MP Full frame (36 x 24 mm ) sized Stacked CMOS sensor and features Digic X processor.
Below you can see the Z8 and R5 Mark II sensor size comparison.
Sensor Size and Resolution Comparison image of Nikon Z8 and Canon R5 II Cameras
Nikon Z8 and Canon R5 II 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
Nikon Z8
or the
Canon R5 II ,
including hyperfocal distance.