Here is the site that explains what all idea sketch can do. I worked on it to create a very simple project that isn’t finished this snapshot will show you what it can do.
So first I create the concept map or whatever you want to call it. I connect smaller ideas to larger ones. It looks like this:
Then you click on the outline button and it creates the outline for you.
You can toggle back and forth between the concept map and the outline. You can add notes of descriptions to each shape as well.