My kids are 5 and almost 3 and already we are extremely cautious of what they have access to. They each have a tablet that we use only for road trips and they are not connected to the internet. They can only use the games, videos etc. that I put on there.
I know there will come a day when they will want a phone (not till high school at least) so I am doing my best to learn my way around the apps, the tricks, the things not only kids, but predators are using to get access to our kids.
There's a school resource officer called Officer Gomez who's posts are going viral because he's sharing what its REALLY like in middle and high schools when it comes to smart phone addiction, vaping, and so much more. Here's just one of his many posts and videos that shows you how easy it is for kids to hide pictures and chats/conversations from parents with an app that looks as harmless as a calculator.