[uv-depression]

That character is actually the en dash (properly used in ranges, e.g. 5–10). The em dash is [shift][option][-]. I would also include triple hyphen in that list; for those of us used to TeX a double hyphen (--) is an en dash and a triple (---) is an em dash.

[_alternator_]

Yup. I use an em dash all the time after I started using TeX. Probably makes my posts look like AI—but it’s worth it.

To get an em dash on an iPhone, long hold the hyphen—it’s the third (longest) option.

(Edit: typo. Using iPhone after all.)

[rogerrogerr]

You aren’t putting spaces before and after the dash - which lowers your AI probability score in my mind.

[latexr]

> The em dash is [shift][option][-].

On the US layout, sure, but there are other layouts where they are switched (i.e. ⌥- is em-dash and ⇧⌥- is en-dash).