Nothing is stopping you from writing fanfiction for college assignments
I have a class where I have to write creative assignments all the time, and let's be honest, I don't always have the motivation to write something super original.
My solution? Write fanfiction and change names and specific details. And you know what? Most college teachers won't even know.
I definitely just wrote a shortened version of a MHA Vigilante!Izuku Dadzawa fanfic and changed names and ages and genders.
I've done it before, and you know what? I got full credit. She didn't even notice.
In conclusion, work smarter not harder. This way, you still practice your writing skills, you practice plot conventions, and you don't have to world build. Plus, if your teacher does notice, you can be like:
So, yeah. Write fanfiction, do crime.