You certainly can! As a world literature program, EWS focuses on foundational stories that provide the inspiration for later works of literature, music, and art. While it is designed to be your main K-8 literature program, there’s no reason to limit your child when there are many wonderful middle grade and YA novels to enjoy.
I suggest selecting a few high-quality novels (and poems and plays) to study formally and allowing your child to choose age-appropriate recreational reading on their own. Maybe they’d like some books with characters they’ve met through EWS? Students will enjoy these books all the more for knowing the source material.
For students in Levels A-C, visit the 398.2 section of your local library for a treasure-trove of folktales. The Rick Riordan Presents series includes lively, imaginative reworkings of world mythology that students in Levels D-F will enjoy. Don’t neglect graphic novels!