If you look at top players, you might notice a slight skewing in sizes there tend to be more tall or short players then the average population. Why is this? Here’s a theory, and a suggestion that might help your game.
If you are tall, then you generally have more power and reach than most of your opponents, but are not as quick. So you develop a game that takes advantage of your power and reach, while adjusting to playing quicker opponents.
If you are short, then you generally are quicker than most of your opponents, but do not have as much power or reach. So you develop a game that takes advantage of your quickness, while adjusting to playing more powerful opponents with more reach.
If you are of average size, then you spend half your time playing taller, more powerful players with more reach, and half your time playing shorter, quicker players. So you end up having to develop two games! One for more powerful players with more reach, one for quicker players.
So there is a natural advantage to being taller or shorter than average. If you are tall or short, take advantage of this. This doesn’t mean a tall player shouldn’t play quick shots, or a shorter player shouldn’t use power, but they should develop their games around their strengths.
If you are average size, then what should you do? Learn to play against both opponents, but develop your game to emphasize one or the other either power/reach or quickness. You can still beat a quicker player if you are almost as quick, while having more power; and you can still beat a more powerful player with more reach if you have almost as much power/reach, and are quicker. So develop more of an all-around game, but emphasize either power/reach or quickness.
Note: if you are average size, and want to develop "reach," what does that mean? Footwork practice, lots and lots of side-to-side footwork practice.