You have a copyright to your outline, as written. No one gets to own story ideas, though. What you do, is don’t share story outlines with people you think are going to use your ideas in ways you don’t want them to. But it’s pretty rare that there would really be a story-writer who wants to use someone else’s story outline to write a story using it. The chances of someone doing that, and being in competition with you in any way, seems vanishing small, unless you have specific rivals who can write stories but can’t invent good outlines, and who are going to try to publish where you are trying to publish. And even if you did have some rival like that, they’d be making themselves ridiculously vulnerable to you outing them for stealing your story line (and for being crazy maniac story-outline bandits, which is ridiculous).