From another thread I found this answer that worked:
SquishyEagle168
Replied on August 17, 2020
**UPDATED 9/19/20**
Here's what worked for me:
(I edited my printer's properties thru Windows & then Edge (and other software apps changed their print dialog to reflect those changes)
1. Start | Settings | Devices | Printers
2. Select your printer | Manage
3. Select "printer properties", and the Printer Properties dialog box will pop up.
4a. Under "General" tab, you'll probably see that it says "double sided: no", and that means any software that uses
your printer will think you don't have double-sided printing capabilities. So, you need to do #4b to fix this.
4b. In the "Device Settings" tab, under "Installable Options", make sure you indicate that "duplex" printing is installed
Once you click OK button for this dialog box, the setting will be saved and all other software apps using your
printer will now know you have dbl-sided printing available.
4c. Not necessary, BUT if you want to force a certain type of double-sided printing (like "flip on long edge"), you can
set that in the Printer Properties dialog box. In the "General" tab, near the bottom, select "Preferences", then
select "Layout" tab. Chose desired option from the "Print on both sides" drop-down box, and select OK & OK again
to save settings.
After you update these settings in the Pribter Properties dialog box, when you open the document with Edge (or any other sw app) & select print, you'll see the option to print on both sides.
Cheers!