The GL and GR buttons, as they're called, add extra buttons on the underside of the Switch's handles, and Nintendo has shared some examples of just how easy it will be to do so. More like this ...

While pressing the button is free, actually using the features its connected to will cost you. GameChat is being folded into the Nintendo Switch Online ... week that showed off new features ...

When the Nintendo Switch 2 ... with paddle buttons. Of course, you don't have to use the back buttons if you don't want to - and I'd actually advise that you turn them off in the system settings ...