It is so important to know if your children are tall enough to ride certain rides BEFORE getting into the parks. Also, do not try to find a way to make them taller so they can go on a ride-the reason is safety. The rides are made safe for certain heights and for that reason it is important to stay within the guidelines. Each park (and park map, hint hint) will let you know what the height requirements are. Check these out before going to avoid any children melt downs.
Here is link for example of Magic Kingdom rides: https://disneyworld.disney.go.com/attractions/magic-kingdom/ Note near top it shows filter for height. You can check out each park and each ride. It helps to know before you go.
Just a helpful hint to make your Disney vacation more magical. Thank you.