https://www.techradar.com/news/xbox-one-x-gets-120hz-display-mode-in-may-system-update

As PC gamers can attest to, getting a high refresh rate monitor can be just as transformative to your play time as a new high-spec computer. Offering smoother gameplay, it's easier on the eyes and makes for a more responsive play session. And now the Xbox One is getting in on the the act.

The following May update for the system will have an option in the Display & Sound > Video Output menu that will let you flip between a standard 60Hz and slick 120Hz display method. That's in addition to the 1440p resolution and variable refresh rate options that were added in the April update.