For Writing
Using Chat GPT to try to replicate how I write, or how any author I like writes, would be cool and a fun way to sort of spark off ideas rapidly. If I had a vague idea about a story I want to tell and could relatively quickly and effortlessly get a few short entries to use as prompts basically that's a huge boon.
I wouldn't want to have it make posts for me, and I wouldn't much respect someone who did. If you're going to write RPs it should be your writing. The same way I feel like using Grammarly or a Thesaurus to punch up your writing artificially is basically cheating and antithetical to being a writer posting Chat GPTs production would be antithetical to being a writer.
Interesting to think about where that might go in the future.
For Visuals
In regard to AI Art, I think it's amazing. Great tool for face claims. Also a great tool, like Chat GPT, for prompts and inspiration. The ability to pick an artist, a medium, and a subject opens things up immensely. My current Discord pfp is a Halfling Barbarian oil painting in the style of Frank Frazetta and it's pretty cool.
In Summary
Much like Chat GPT finishing your favorite unfinished series (Game of Thrones, Dark Tower, Stormlight Archives) or continuing a beloved series (Harry Potter, Ender's Game, Lord of the Rings) mimicking a style of writing will not mimic the inspiration and invention of the writer that made you love those series in the first place. At least not for another few years and then wooooweeee it's over.
In the same way you can get an idea of what defined one artist or another's style during his or her life, but it can't guess how that artist's talent and tastes might have developed. If all you have of Picasso is his Blue Period you're only ever going to see a subsection of his genius.