Outlines are well known tools for writers. Many writers like to use them as a way to help discover and plan the story before they begin writing, while others look at the outline with some dismay. Regardless of how you view outlines, they are well-known for a reason.
It’s important to remember that an outline isn’t concrete. Think of it more as a guideline that can change just as the needs of your story change. It can change just as much as your story does.
The other really important thing about an outline is that you don’t need it before you start writing that first draft. In fact, you may find it more useful to create an outline after you’ve written the story, to help you edit. I’ve found this helps identify extraneous scenes, but also to help build support for saggy middles.
Outlines also take a lot of different forms. List, bullet points, flow charts, summaries. There are about a dozen different ways to create an outline. And like everything else in writing, the only one that’s guaranteed to work is the one that works for you. Trial and error are your friends.