I’m not aware of many writing instances, in fact.
My observation about writers is they’re rather spread all over the fediverse. And even on places like writing.exchange, people don’t always toot about writing (I’m guilty too).
My suggestion is search hashtags #writing, #amwriting, #editing, #nanowrimo, #fiction, #nonfiction, #narrative, etc and find/follow people that way. Don’t forget whatever genre tags your interested in.