In fact, on macOS and iOS simply typing two dashes (--) gets autocorrected to an em dash. I used it heavily, which was a bit sloppy since it doesn't also insert the customary hair spaces around the em dash.

Incidentally, I turned this autocorrection off when people started associating em dashes with AI writing. I now leave them manual double dashes--even less correct than before, but at least people are more likely to read my writing.