https://www.cnet.com/news/apple-brings-dual-sim-support-to-the-iphone/

Apple's letting you embrace your inner duality with your iPhone. At Wednesday's Apple event, the company announced the launch of Dual SIM support for the iPhone. Both the iPhone XS and the iPhone XS Max will offer the Dual SIM card option. 

This will allow you to have two different phone numbers and two different carriers on the same phone. While that sounds like a feature you'd only use if you have something to hide, it'll be quite useful if you want to make your personal phone and work phone the same device. During an incoming call, you'll even see which number the call is for, so you can ignore it if it's a work call during your vacation.