If you can’t find a specific thing, just searching “how to x in markdown” in your preferred search engine should net you an answer if x is supported.
There are also many markdown editors that can be run either locally or through a browser; these can be useful if you want to test some syntax without putting any mistakes in the eyes of the public. I like Obsidian for local editing and usually recommend this one for online testing.
You can end a line with a backslash to have single line line breaks.
Lemmy just uses markdown, so any good guide for that should be able to help you:
https://www.markdownguide.org/basic-syntax/#line-breaks
If you can’t find a specific thing, just searching “how to x in markdown” in your preferred search engine should net you an answer if x is supported.
There are also many markdown editors that can be run either locally or through a browser; these can be useful if you want to test some syntax without putting any mistakes in the eyes of the public. I like Obsidian for local editing and usually recommend this one for online testing.
Hope all that helps!