Ahh yes padawan, there is a way to increase the size of a bonsai before putting it in a display pot! You can either plant it in the ground if it is tolerant of the weather in your climate, or you can put it in a much larger pot. When it has reached the desired size, you start the process of getting it ready for the display pot, which takes time. Root pruning and trimming back the excess growth is needed, then time for recovery after doing it. Basically it goes in a smaller and smaller pot until it finally goes in the display pot, where only the occasional root pruning and normal pinching/whatever maintenance the species needs is done.