Greetings Lori and welcome to the Disney Parks Moms Panel!
I am so happy to hEAR that your son is interested in participating in
Jedi Training: Trials of the Temple. This is a must-do activity for my 7-year-old daughter whenever we visit Disney’s Hollywood Studios. Eligibility to participate in this amazing activity is based on age, so if your son is 12-years-old he will be fine, regardless of his height. Last time my padawan participated there were taller younglings in the group and it was not an issue!
Moms Panel tip: if this is important to your son I highly recommend arriving as early as possible to secure a spot for him in one of the shows that are offered during the day. Please register at the Indiana Jones Adventure Outpost located between the Indiana Jones Epic Stunt Spectacular! and the 50's Prime Time Café, and don’t forget that he must be with you at the time of sign-up.
I hope this helps you while planning, Lori! Please stop by real soon if you have additional questions.
May the Force be with you!
Thiana