Funny reading through a lot of the comments and realizing so many of these techniques are all present in a book I recommend here pretty often.

XX by Rian Hughes has multiple character perspectives that meet up, stories within stories, directly references the reader themselves or the page they're reading, uses the white space and text layout to indicate what's happening in the story as well as crazy fonts, hell even uses emails in the text like one person mentioned.

It's an absolutely bizarre book that I can't get out of my head