Doc Edward Morbius ❌@lj_writes Yes, text editor: vim. I've used it (or vi precursors) for over 30 years now.
As well as a slew of word-processors and other editors, none of which have stuck, emacs excepted.
For both Markdown and LaTeX, a paragraph is indicated by a double carriage return (two line breaks). That's then typeset according to the style rules when rendered.
Double-spacing as an end-of-sentence convention makes finding sentence boundaries far more reliable as well ;-)