Leica SL2 has a
47.0MP Full frame (36 x 24 mm ) sized CMOS sensor and features Maestro III processor. On the other hand, Sony A1 has a
50.0MP Full frame (35.9 x 24 mm ) sized Stacked CMOS sensor and features Dual Bionz XR processor.
Another difference between these two cameras is that Leica SL2'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 SL2 and A1 sensor size comparison.
Leica SL2 and Sony A1 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.