There are quite a few things for kids, but Universal is more of a thrill park with a decent amount for kids, whereas Disney is primarily stuff
everyone can enjoy with a few thrill rides.
There is an entire land for kids (and kids at heart) at both parks. There’s also quite a few characters, and a parade with meet and greets at the end. There’s several shows that are either directed at kids or kid-friendly. You can also use rider swap so all the adults can experience the stuff
the kids don’t want to or can’t. The website lists all the attractions, including height requirements, as well as the shows. For the eldest, experiencing the wizarding world alone will be worth the visit.