See the original markdown specification (bold mine):
The implication of the “one or more consecutive lines of text” rule is that Markdown supports “hard-wrapped” text paragraphs. This differs significantly from most other text-to-HTML formatters (including Movable Type’s “Convert Line Breaks” option) which translate every line break character in a paragraph into a
tag.
When you do want to insert a
break tag using Markdown, you end a line with two or more spaces, then type return.
Just add at the end of line. For example
one
two
Will become
one
two
It’s also better than two spaces because it’s visible.
Edit:
It doesn’t work in some markdown applications, so it may cause incompatibility.
https://www.markdownguide.org/basic-syntax/#line-break-best-practices