The sun is not actually appearing over the horizon during a sunrise as the earth “spins on its axis,” nor is it disappearing under the horizon during a sunset. A sunrise is simply the sun coming into view from our perspective as it travels in its circular path around the center of the earth (the North Pole). And a sunset is the sun disappearing from our perspective as it travels further away from us along its circular path. Simple.
Here below is a very good analysis of the phenomenon of sunrises and sunsets as we see them from our perspective on a flat earth.