Microsoft Windows has the MS Paint program, which is a great way for users to have very simple picture editing and creating abilities. But, ChromeOS doesn’t have a built-in app like this.
PaintZ (which was recently updated to version 3.0) is sort of an MS Paint clone, but for ChomeOS. Of course, its web-based, so you’ll need to be connected, but it does provide the same, simple picture editing and creation features.
Go here: https://paintz.app/
When you need something with better capability, check out Pixlr, which is covered here: Tip: Best Snagit Replacement for ChromeOS