[crimony]

Microsoft Word automatically converts dashes to em dashes as soon as you hit space at the end of the next word after the dash.

[BLKNSLVR]

That's the only way I know how to get an em dash. That's how I create them. I sometimes have to re-write something to force the "dash space <word> space" sequence in order for Word to create it, and then I copy and paste the em dash into the thing I'm working on.

[robin_reala]

Option shift - in macOS (option - gives you an en dash).

[leoc]

Windows 10/11’s clipboard stack lets you pin selections into the clipboard, so — and a variety of other characters live in mine. And on iOS you just hold down -, of course.

[Terr_]

Alt-0151 on the numpad in Windows.

Long-press on the hyphen on most Android keyboards.

Or open whenever "Character Map" application that usually comes with any desktop OS, and copy it from there.

[dboreham]

You can Google search "em-dash" then copy/paste from the resulting page.

[cwnyth]

Ctrl+Shit+U + 2014 (em dash) or 2013 (en dash) in Linux. Former academic here, and I use the things all the time. You can find them all over my pre-LLM publications.