I've seen a lot of promotion recently for courses that purport to show you how to make loads of money writing children's books and selling them on Amazon.
One of them shows you have to use clip art or public domain art for the illustrations.
Another suggests you hire people on Fiverr.com to do the illustrations for you for five dollars each.
Then you put your book on Amazon and wait for the money to roll in.
Prepare for a long wait.
Kids like holding books or sitting in their parents' laps while being read to from a traditional book.
Also, if you're very skilled maybe you can put together an attractive book with public domain illustrations or Fiverr art, but it's not easy.
The biggest question is how you get people to become aware of your book so that somebody buys it. Just putting it on Amazon is like throwing a message in a bottle into the ocean.
If you want to write a kids' book for fun or maybe as a present for your grandchildren, by all means go ahead. You can easily set it up as a print-on-demand book. Once in a very great while, such a book could take off.
Just don't count on it, and don't spend a lot of money on a course that pretends success is practically guaranteed.