https://thenextweb.com/apple/2018/10/23/apple-says-r-the-iphone-xr-just-means-r/

We’ve spent weeks scratching our heads over what the ‘R’ in the new iPhone XR stands for. And finally we’ve got a definitive answer to this great mystery: It just means “R.”

Apple’s VP of marketing, Phil Schiller spilled the beans in an interview with Engadget and said that XR and XS are just letters with no special meanings attached to it.