iPhone adapter

I have a Bose radio we purchased about ten years ago. When we purchased the radio, we purchased a device that plugged into the radio and our phones so that the music on our phones played through the radio. At that time we had maybe iPhone 5? We now have iPhone XR and need an adapter that will allow us to plug our current phones into the Bose radio. I have talked to Bose and they said I could buy an adapter from Apple. I have looked on line in the Apple store, but did not find what I need. I would appreciate any help and/or information. Thanks!