Anatomy of a Fall is not based on a true story. It's a completely made-up narrative crafted to engage and entertain the audience through fictional elements and plotlines.
One possible theme could be failure. Since it's about a fall, it might explore the reasons behind a particular failure, be it personal, professional or otherwise.
I'm not entirely sure specifically what the 'Anatomy of a Fall True Story' is about without more context. However, generally speaking, if it's about a true story, it could be about someone's personal experience of a fall. This could be a fall from grace, like a person losing their reputation or status. Or it could be a physical fall as mentioned before. It might explore the emotions of the person who fell, such as fear, embarrassment, or anger, as well as the reactions of those around them.