Both Olympus E-M1X and Canon R6 have 20.0 MP resolution sensors but Olympus E-M1X's sensor is Four Thirds (17.4 x 13 mm ) and Canon R6's sensor is Full frame (36 x 24 mm ).
Since Canon R6's has a larger sensor area with the same resolution, this means that it also has a larger pixel area hence better light collecting capacity for a given aperture compared to Olympus E-M1X.
Below you can see the E-M1X and R6 sensor size comparison.
As seen above, Canon R6 has a 3.8x Larger sensor area than Olympus E-M1X. 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.