When will support for Xr end?
I read somewhere it would be supported until iOS 18 comes out. Anyone know when that would be?
Only Apple can say for certain. I don't believe they have yet released a list of which phones will support iOS 18.
If you mean how long will you be able to get service or repairs on the phone, that's generally 5 years after when Apple stopped selling it.
If you're considering buying a used phone, I'd go with a later model, at least an iPhone 12. If it's a phone you already own, I'd probably hold on to it until the fall when new phones are generally released.