Well, the first thing that occurs to me is Burnett's A Little Princess which is all about the power of storytelling to give a person strength and affect the lives of the people around them: one of the pivotal plot moments is the heroine, while starving herself, sharing bread with another starving girl because she feels it's what the princess she imagines herself to be. And then the world "magically" changes when her imaginings are overheard and her neighbors decide to make them real.

In the "slightly more of a stretch" category, there's Georgette Heyer's Sylvester, Or: The Wicked Uncle, where the plot centers around the gothic novel the heroine writes, and its uncomfortable (but misleading) resemblance to real world people, including especially the hero, who she's cast as the villain of her plot.

You could also maybe class the folktale The Robber Bridegroom/Mr. Fox and its variants as part of this tradition, as the climax centers around a woman telling a story and the man denying its truth until it's revealed as truth.