Can't print double sided with Brother printers through AirPrint

I have been able to do duplex printing on a Brother laser printer while using Air Print on my M1 Mac running Big Sur & Ventura (printer is probably about 10 years old). All I can remember is that I created & saved a Preset option with the duplexing or two-sided print option enabled when I went to print a job. I probably had to select the "Print Using System Dialog" option to do so which is the older interface....I don't know if this is still available in later versions of macOS.

If there is no way to configure duplex printing within macOS, then you can try making duplex printing the default setting on the printer itself. I'm not at my printer so I cannot check if they may have the configuration option. Of course this would mean every print job sent to a printer configured this way would be using double sided printing.

Of course this assumes your printer actually has a built-in automatic duplexer.

Your title is correct as written.

To use printer-specific features, you must be using the manufacturer's Driver software. Especially for older Printers, there may not be a Printer-specific driver that works under macOS Catalina or later, when Apple said "no more 32-bit software allowed.".

if you have book-length documents to print, Readers can make some suggestions about physically flipping the pages over and printing the backs as a second pass. just ask.