“When she gets a scholarship to an art school, quirky high schooler tries to convince her overprotective family she’s pregnant, so she will be ‘sent away to her aunts’ in order to, in reality, go to the art school in New York.”

It’s a good start. You could include a reference to “sexist male dominated culture of the sixties” in the longline. If the character arc you want to show includes the protagonist becoming more self motivated, grounded, etc, then we would need to understand better the stakes of her failure to take this action. Like, if she doesn’t tell this lie, she will be married off in an arranged marriage, and lose her one chance at pursuing her life dream of being an artist. Or you could make it more interesting perhaps by making the aunt be “in” on her scheme. The aunt may be a mentor figure who herself has missed out on her dreams in life, perhaps the only person who believes in the protagonist and demonstrates unconditional love. The aunt can achieve joy in life, despite her own life regrets, by helping the protagonist and covering for her with her overprotective family.