Meta often means “one layer up,” e.g. “metaphysics” is the way of the world that our mundane world is embedded in. A reader might remark that the book Gödel Escher Bach is “pretty meta,” which might mean it breaks the 4th wall.
The opposite to meta is mesa. For instance, AI safety researchers sometimes talk about mesa-optimizers, meaning an optimizer which itself is optimised by another optimiser.
Facebook’s metaverse is apparently misnamed – seeing as it runs on computers which are in our own universe, it really ought to be called the mesaverse, and our physics are its metaphysics.
The Meta is a character in the hit internet series Red vs Blue.
Yeah you could apply the word to a story-in-a-story like The Princess Bride, which has a narrative about a boy hearing another story. The meta-narrative would be the story about the boy.
You don’t need to get recursive with the layers of fiction though. If you imagine a long-running many-hundreds-of-episodes tv show, the show will likely be divided into a number of distinct arcs, perhaps season-by-season. Each arc will have its own narrative, its own story beats, its own themes; but all the arcs will be tied together by a metanarrative, a narrative encompassing the other narratives.