Google-docs – How to make an en dash in Google Docs

In the Special characters dialog, you can type in dash in the search box and one of those is an en dash.

If you are using Windows, you can use the numeric keypad to enter an Alt code.
(For en dash: Alt+0150)

Alternatively, you can copy and paste one in.

From Google Docs help:

Insert special characters

You can add special characters into your documents and presentations, such as arrows, shapes, or accent marks.

1. Open your document or presentation.
2. Click the Insert menu.
3. Select Special characters. You can use the drop-down menus to explore categories of characters, or, if you know the Unicode value for the character you’re looking for, you can enter it into the "Hex input" text field.
4. After selecting a character, click the Insert button to add it to your document.