Complex sentence: Cleo (Rowan Blanchard) is a teen girl living in the shadow of her popular older sister, Molly (Paris Berelc), the most popular girl at school and recognized by everyone, but Cleo is barely noticed by anyone else.
Split into simpler sentences: Cleo (Rowan Blanchard) is a teen girl who is always living in the shadow of her popular older sister, Molly (Paris Berelc). Her sister is the most popular girl at school and recognized by everyone, but Cleo is barely noticed by anyone else.