Hi, Amanda!
Thanks so much for reaching out to the Disney Parks Moms Panel!
This was a big concern for me when my son turned ten (four years ago - yikes)! When we asked about the kids' menu for a ten-year-old at any sit-down table-service restaurant, cast members allowed him to pick something from the kids' menu but he was given a larger portion.
When it comes to a buffet meal, your 10-year-old can eat any adult or children's meal. When it comes to quick service, he's welcome to order from the adult or the children's menu! Keep an eye out for
Mickey Check Meals! Those follow dietary guidelines and help your son follow healthy eating practices!
I hope that helps with your planning! I know you're going to have a great visit to Walt Disney World Resort!
Let me know if I can help answer any additional questions!
-Jen