Leica D-Lux Typ 109 has a 13.0MP Four Thirds (17.3 x 13 mm ) sized CMOS sensor . On the other hand, Sony RX100 IV has a 20.0MP 1 (13.2 x 8.8 mm ) sized BSI-CMOS sensor and features Bionz X processor. Sony RX100 IV's sensor provides 7MP more than Leica D-Lux Typ 109'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.
Below you can see the D-Lux Typ 109 and RX100 IV sensor size comparison.
As seen above, Leica D-Lux Typ 109 has a 1.9x 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.