Both Nikon A100 and Nikon S3500 have 20.0 MP resolution sensors but Nikon A100's sensor is 1/2.3' (6.17 x 4.55 mm ) and Nikon S3500's sensor is 1/2.3-inch (6.16 x 4.62 mm ).
Since Nikon S3500'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 A100.
Below you can see the A100 and S3500 sensor size comparison.
Nikon A100 and Nikon S3500 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.