Recommendation where authors play with language.

I’m unsure how to accurately convey what I’m looking for, but I’ll try!

I’m after books in the same vein as Flowers for Algernon or The Book of Koli series which, while being wildly different in terms of genre etc., have similarities in the way they’re written. For example FFA’s language evolves as the main character changes, and BOK has spelling errors to the point where you have to actively work out what the characters mean/are trying to say.

Thanks!