Let’s consider an example of an imaginary planet. In this solar system, the planet completes one orbit around the sun in 8.6 solar days, rather than the 365 days that Earth does. (I use the shorter year because it magnifies the difference between the sun and sidereal days so you can see it more easily.)
This is a display that shows the sun and the stars The difference between the animation of the planet’s days. The arrows show when a point on the planet points to a distant star (which would be the out-of-frame way) or its sun. The moment it points towards the sun, the sun will be at its highest point in the sky for observers at that location.
Note that for a sidereal day, the planet does make one full revolution – 0.648 “time units”. (I also made up imaginary units of time for this example.) However, at this point in the motion, the sun doesn’t return to the same place in the planetary sky because the planets moved during that sidereal day. It takes 0.726 “time units” before the arrow points to the sun. So, in this case, the solar day is a little longer than the sidereal day, just like on Earth.
It is possible that the solar day is shorter than the sidereal day ? Yes. If a planet spins in the opposite direction of its revolution, that reverse rotation will bring the Sun back to its highest point more quickly. It looks like this: