Dear fellow fediverse netizen.
If you find yourself more than once every six months needing a "thread" kind of function, meaning you want to write more than the standard 500 chars your instance gives you, please do yourself, us, and the fediverse at large a favor and find an instance that does not use those outdated, arbitrary, and artificial character restrictions.
The fediverse was built, largely, to transport all manners of media. The "Note" type can, technically, do much more than 500 chars, but should not ever have line breaks. That's what "Article" is for. Now, someone (cough, cough) thought it'd be cute to look like the Birdsite and used an impulsive limit to 500 chars while going against the standard and using the Note type.
That bell can't be unrung. But the moronic character limits can. Many instances give you more than 500 chars, use them. Threads in the fediverse don't work well. The Birdsite, historically an SMS service, thus the 140 chars, at least displays such threads in a somewhat legible manner. Many instances on the fediverse won't. Even if the very same mind that cursed one instance software with that idiotic 500 char limitation, would implement something to that effect, nine out of ten instance softwares won't.
Just write more. Find a place that does not infantilize you down to a guppy brain caveman conversation. Or, well, stay with those short grunts. But don't thread. Please.