Depends what formatting you want to keep.
Pandoc is one set of methods, but can be tricky to set up if you don’t understand it and are particular about end result. There’s an Obsidian plugin.
Typora uses pandoc and does a pretty good job.
Alternatively there’s the Word add-on Writage which reads and saves markdown directly into Word.
Typora and Writage aren’t free, though notvery expensive.
can be tricky to set up if you…are particular about end result.
I think it’s foolish for most people to try to control the design of the final document from a markdown app or Pandoc. As long as the basics of formatting—italics, bold, headers, lists, etc.—come through, it’s much easier to control things like typography and layout once it’s in Word or another rich text WYSIWYG word processor or page layout program, because that’s what they’re designed to do.
I know people try to do it, but even when they more or less succeed it seems misguided to me. Markdown was designed explicitly so you can write quickly without worrying about or being tempted to fiddle with the final formatting while you’re writing copy. Markdown just adds some very basic notation to denote things like hierarchy and emphasis without actually formatting the (plain)text. It’s not supposed to mimic rich text.
Personally, I’d either use Inspire Writer or Ulysses (very good preview) or Writage and Word.
There’s also Marked 2 for Mac users, though last I tested it iA Writer (despite having far fewer templates) does a better job of converting markdown heading levels into their Word equivalents.