Both Fujifilm Z900EXR and Nikon S6900 have 16.0 MP resolution sensors but Fujifilm Z900EXR's sensor is 1/2-inch (6.4 x 4.8 mm ) and Nikon S6900's sensor is 1/2.3' (6.17 x 4.55 mm ).
Since Fujifilm Z900EXR'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 Nikon S6900.
Below you can see the Z900EXR and S6900 sensor size comparison.
Fujifilm Z900EXR and Nikon S6900 have almost the same sensor size, so neither of them has any significant advantage over the other in terms of providing control over depth of field when used with the same focal length and aperture.