Well, it might be that the princess discovers a secret room in her castle. Inside the room, there are ancient spells and potions. She starts to study them and accidentally turns her maid into a frog. Then she has to figure out how to reverse the spell. Along the way, she learns more about magic and becomes a better ruler because she now understands the power and responsibility that comes with it. This all could be part of a short princess story.
A short princess story may involve the princess having to deal with a mean stepmother. Just like in some classic tales. The stepmother might try to stop the princess from inheriting the throne. The princess, though, would show her strength and kindness. She would win over the people of the kingdom with her good deeds, like helping the poor and sick. Eventually, the people would support her claim to the throne, and she would become a great queen.