Fujifilm X-T5 has a 40.2MP APS-C (23.5 x 15.6 mm ) sized BSI-CMOS sensor and features X-Processor 5 processor. On the other hand, Canon T6i has a 24.0MP APS-C (22.3 x 14.9 mm ) sized CMOS sensor and features DIGIC 6 processor.
Fujifilm X-T5's sensor provides 16.2MP more than Canon T6i'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-T5'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 X-T5 and T6i sensor size comparison.
Sensor Size and Resolution Comparison image of Fujifilm X-T5 and Canon T6i Cameras
As seen above, Fujifilm X-T5 has a 1.1x Larger sensor area than Canon T6i. 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.