

Most people aren’t taking the time to type in ctrl+shift+u+2+0+1+4 when a regular minus-dash would get the point across with a single keystroke.
emacs:
-
C-x 8 _ m
-
C-x 8 RET e m SPC d TAB RET
emacs using input methods
-
C-\ T e X RET
to enter TeX input method.- - -
to enter an em dash when in that input method. -
C-\ s g m l RET
to enter sgml input method.& m d a s h ;
to enter an em dash when in that input method. -
C-\ r f c 1 3 4 5 RET
to enter rfc1345 input method.& - M
to enter an em dash when in that input method.
For X11 or Wayland, if you have assigned a key to be Compose: Compose and then three hyphens to get an em dash.
The stuff there is a heck of a lot easier to input than memorizing numeric Unicode codepoints and using GTK’s control-shift-U thing that the parent post was suggesting.
Emacs also can do that (
C-\ u c s RET
to enter ucs input method, andu 2 0 1 4
with that input method enabled), but it’s almost certainly not how you want to input oddball characters unless you’ve no other choice.