You'd be surprised what kids can figure out or stumble across. I remember 2 times that my son totally blew me away. The first time was as a toddler, I gave him my feature phone to listen to kidz bop, and next thing I knew I had a bunch of new photos and videos. I finally had to give him the phone and have him do it while I watched to see how he was opening the camera. He found a shortcut I didn't even know existed. The second time he was a little older but I woke up to a notification from YouTube about a video I posted. He was 7, 8 maybe at most.
There is a lockscreen app that locks them into a play zone where you can pick items for them and it also generates things for them, it works off of their birthday so it's supposed to be age appropriate. If it's compatible with your device it's called
Kids Mode.