Fujifilm X100V has a 26.0MP APS-C (23.5 x 15.6 mm ) sized BSI-CMOS sensor and features X-Processor Pro 4 processor. On the other hand, Sony RX100 VII has a 20.0MP 1″ (13.2 x 8.8 mm ) sized Stacked BSI-CMOS sensor and features Bionz X processor.
Fujifilm X100V's sensor provides 6MP more than Sony RX100 VII'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.
Another difference between these two cameras is that Fujifilm X100V'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 moire occurring in certain scenes.
Below you can see the X100V and RX100 VII sensor size comparison.
As seen above, Fujifilm X100V has a 3.2x Larger sensor area than Sony RX100 VII. 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.