When my kids were that age they loved the kids encyclopedia that we bought for them. There are a bunch of different ones, just check Amazon. The good ones have great pictures and give facts about a wide variety of subjects. At 5, someone would need to read the pages with them, but that's a good thing!
For example, here's one from the Smithsonian: https://www.amazon.com/New-Childrens-Encyclopedia-Visual/dp/146547451X