You really can get your child a meal they will enjoy without having to be dishonest in front of them. When DS was 11, he still ordered off the kids menu at DW all the time. Never was questioned or age asked. As long as the amount of food is ok you should be fine. if you need more food. most places will fix an adult size serving of a kids meal for a higher cost.
Most any place will also taylor an adult meal to suit your child. MANY places did this for my picky 14 year old on our last trip in Jan. One place simplified a pasta dish, another made his steak plain. One did fries instead of a veggie and another put each item on a plate so the food did not touch.

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You might have to pay what is expected of you to pay but you will be able to please your child. Of course buffets would be at adult price.
Unless it is special meal like CP or Fantasmic, it really should not matter what age your child is listed at on the ADR.