Hey Les,
Welcome to the forum! 
Always try searching with the search field the Keyboard Maestro Editor Help Menu – you never know what you'll find -- actions, text-tokens, functions, and menu-items...
If you haven't read this it's worth a couple of minutes of your time.
Tip: How Do I Get The Best Answer in the Shortest Time?
In answer to your question, here's a sample macro:
Date and Time -- ICU Date Construct.kmmacros (4.1 KB)
Change the keyboard shortcut to your desired chord.
The other date patterns you wanted are:
•1/11/19 ⇢ •%ICUDateTime%M/dd/yy%
1-11-19 ⇢ %ICUDateTime%M-dd-yy%
Keep in mind that it's generally worth searching the forum a time or two for what you need:
https://forum.keyboardmaestro.com/search?q=insert%20date
And it's worth looking on the wiki:
https://wiki.keyboardmaestro.com/Dates_and_Times
-Chris