Barbie and the Secret Door (2014) on Netflix

Plot summary

In a modern kingdom, Princess Alexa avoids the duties expected of a royal daughter because she is shy. Her grandmother hopes to encourage her with a storybook about a princess who learns she has magic, and while Alexa reads it, she notices a secret door in the gardens of the royal castle. Beyond it lies a magical land where her dress changes and a wand appears in her hair. She meets Nori, a fairy whose wings are gone, and Romy, a mermaid whose tail has turned into legs. Both are sure that a princess with magic can put things right. Their realm is threatened by Princess Malucia, a spoiled child born without magic who takes it by force from the creatures she captures. The realm's fairies, mermaids and unicorns hide from her in a glade.