This is probably possible now. Back when machine learning was all the rage people were using it to identify authors of various anonymous works. It became an introductory project to identify the Federalist Papers authors. Just read in some works, identify patterns, set up tests, and set the LLM into a loop testing whether the output would be predicted to be the author you are trying to impersonate.
https://towardsdatascience.com/hamilton-a-text-analysis-of-t...