I had to swap my IPhone XR to a IPhone 6 s plus, and the contact and phones never transferred. How do I get that done?

Unlike some Android devices, contacts are neither stored locally on an iPhone nor in SIM. They are synced to an email account that you had Google, iCloud, AOL, Exchange, Outlook, Yahoo or any Other

If Contacts on iCloud, try this --> Restore contacts, calendars, bookmarks, and more using ...

Else add the email account that stores your contacts.

If you turn on Messages in iCloud & iCloud Photos, your content is automatically stored in iCloud and is available on all devices that use the same Apple ID