iOS 12.1 beta 1 enables eSIM functionality, but you’ll need to wait on your carrier – 9to5Machttps://9to5mac.com/2018/09/26/ios-12-1-beta-1-esim-functionality/
The embedded SIM (eSIM) functionality in the iPhone XS and iPhone XS Max, a feature that will enable dual line support in the latest flagship iPhone, can be found in the latest iOS 12.1 beta. So far three of the major US carriers — Verizon, AT&T, and T-Mobile — have pledged support for eSIM. The rollout will likely occur after the official launch of iOS 12.1. The iOS 12.1 update also includes support for Group FaceTime for up to 32 people, a new real-time Depth Control slider that can be used when taking Portrait Mode photos, and, with watchOS 5.1, new color watch face options in the Apple Watch app.