Yes, a 3-year-old can certainly go, but the experience is quite different for them compared to older children. Children under age 3 enter for free, so a 3-year-old will require a paid admission ticket. At this age, many of the park's "thrill" attractions, such as Jurassic World – The Ride or Revenge of the Mummy, will be off-limits due to height requirements (typically 42–48 inches). However, they can enjoy the Super Silly Fun Land play area, the Secret Life of Pets: Off the Leash ride, and various character meet-and-greets with figures from Minions or Sesame Street. It is highly recommended to bring a stroller, as the park involves significant walking and navigating the long escalators (Starway) between the Upper and Lower Lots. Universal also offers a "Child Switch" program, allowing parents to take turns riding the big attractions while one adult stays with the toddler.