Connect iPhone 6 display to iPhone XR iPhone XR display and digitizer not working. Need to access phone to retrieve some data. How can I unlock the phone, so I can backup from computer? I bought a replacement screen, but my cat managed to eat the cables before I can successfully install it... I have an old iPhone 6 at my disposal, can I just connect that screen to the iPhone XR? Will it work at all?
No.  

Just a visual comparison of the iPhone 6 and the XR tell you that besides the differences in screen sizes, the connectors and connector locations are very different.  The 6 connects from the top where the XR connects from the side.