Sorry for what I'm sure is a very simple question, but I'm terrible with computer technology and confused as a result

I just bought an Archer AX6000 on the advice of a sales guy who advised be to go with this newest tech so I wouldn't have to upgrade for a long time.

Now I need to buy a modem for it.  Does it need to be a WiFi 6 capable modem?  Are there recommended modems to go with my router?  Using Xfinity

and live in a 2000 sf home with 2 adults using internet and a 5 yo grandaughter watching her cartoons on her kid tablet.

Thanks for your input and sorry if this has been answered 1000 times before