In the world of the sequel, the original is only fiction.
Usually, a sequel shows what happened next in the world of the original work. This trope is when a sequel or spinoff shows what happened next in a world where the original work is only fiction. A common aspect is that although the sequel is generally constrained to be the same genre as the original (otherwise, why make it a sequel?), setting it in a different world allows the creators to go as Broad Strokes as they like, and play with things not working according to the rules viewers would expect from the original. May include an invocation of The Fourth Wall Will Not Protect You, especially if it's in the horror genre.