Start with high-confidence ya mindfulness & meditation books, then narrow by subgenre or adjacent topics.
5-minute Devotions for Teens
Laura L. Smith
Sunny Days Ahead
Lindsay Franklin
Winning the War in Your Mind for Teens
Craig Groeschel
Calm Your Anxious Mind
Carrie Marrs
Wide Awake
Diana Winston
Zen in the Art of the Sat
Matt Bardin, Susan Fine
Eat Well and Feel Great
Tina Lond-Caulk
Just As You Are
Michelle Skeen, Kelly Skeen
10 Minutes to Better Mental Health
Lee David, Debbie Brewin