Fujifilm X-T30 II has a 26.0MP APS-C (23.5 x 15.6 mm ) sized X-Trans CMOS sensor and features X-Processor 4 processor. On the other hand, Samsung NX mini has a 20.5MP 1' (13.2 x 8.8 mm ) sized BSI-CMOS sensor .
Fujifilm X-T30 II's sensor provides 5.5MP more than Samsung NX mini'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 X-T30 II'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 X-T30 II and NX mini sensor size comparison.
As seen above, Fujifilm X-T30 II has a 3.2x Larger sensor area than Samsung NX mini. 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.