In File-Page Setup-Layout

And printer settings.

This is my discovery.

The setting of duplex printing is a function of the printer, which means that you can print documents on both sides only if the printer has duplex printing function. If your printer has double-sided printing function, click the Print option under the File menu in WORD to open the Print dialog box, and then click the Properties button to the right of the Printer Name to enter the printer properties dialog box. I have a "duplex printing" option in the Layout tab of the Properties dialog box, as long as your printer has duplex printing.

If not, you can also use a single-sided printer for manual double-sided printing.