The only important thing is to let the editor and typesetter know that you want space(s) inserted between a pair of paragraphs. You can't do that by putting in an empty line (or lines) because as editing takes place those empty lines may end up at the top or bottom of a page.
All the publisher needs to know is that you want a break in the text. In the published version, this might be one line, two, or three, or might include some cunning little dingbat the designer wants to put there. This isn't really your business, and whether you put # or * or ### or *** or (as I do, for emphasis) * * *, your editor will interpret that as "break here." The style of the break, like the font of the book, is up to them.
I break between scenes in a chapter.
I also break between points of view in a chapter, if the chapter switches POV; but some very good writers don't always do so. (Larry McMurtry, Ann Patchett, Patrick O'Brian.)
And many, many bad writers don't break between POV changes.