Sony RX100 IV has a 20.0MP 1" (13.2 x 8.8 mm ) sized BSI-CMOS sensor and features Bionz X processor. On the other hand, Leica X Vario has a 16.0MP APS-C (23.6 x 15.8 mm ) sized CMOS sensor .
Below you can see the RX100 IV and X Vario sensor size comparison.
As seen above, Leica X Vario has a 3.2x Larger sensor area than Sony RX100 IV. Larger sensors give photographer more control on the depth of field and blurry background compared to smaller sensor when shot in same focal length and aperture.