How do I type the power icon on an Apple Keyboard?
Go to Edit > Emoji &amp; Symbols, click on the gear wheel at top left, select Customize, check the box for Unicode, then find 23FB.  If blank, download and install the font Symbola.

https://www.fileformat.info/info/unicode/char/23fb/index.htm

(From the keyboard, you need to activate the Unicode Hex input source in System Preferences/Keyboard/Input Sources and then type 23fg while holding down the Option key).