A relative of mine has a Toyota Avalon and recently had the windshield replaced.
And now the camera for the lane assist, and adaptive cruise (?) won't calibrate.

The windshield was not replaced by Toyota. But the dealer has now tried two cameras and they can't get it to recalibrate. They say it must be the windshield.

Any ideas?

Take it back to the installer? It is OEM glade right? If not, the. That's where I'd start.