Idea: Try making every bullet of your outline wrong
I hate outlining stories, but recently I had an idea that seemed like a fun exercise to try. The idea is to write the outline, then make it wrong. I haven't tried it yet.
So first you write your outline and let it be garbage. Let it be boring and straightforward and stereotypical and generally "bad." Ideally make them detailed, too, because that will give you more choice later on.
Next, write something inspired by the outline, but with a twist: You are going to make every bullet wrong. It's up to you how to make them wrong. You could make it not even wrong, you could make it mostly right but wrong in the details, or you could make it wrong in some other way. This is where the story becomes surprising.
This is somewhat inspired by the one exercise in Stephen King's On Writing, which gives you a long setup and then a twist to write into it. Also inspired by Jacob Krueger's idea of surprising yourself which I wrote about here.