https://www.techradar.com/news/ios-121-beta-activates-esim-on-iphone-xs-and-xs-max-with-a-catch

There's another perk to updating to the iOS 12.1 beta: the promised iPhone XS and iPhone XS Max eSIM support is now live. Of course, there's a catch.

Apple's eSIM technology allows for dual-SIM-like functionality using two lines at once, and it is in the iOS 12.1 settings now, as first spotted by 9to5Mac. But activating the eSIM still requires carrier support to become functional.