URGENT/ ASAP iPhone xr lens replacment without breaking backglass

Heat up the new one so it’s hot to the touch then gently push the glass out from the back. Then replace the broken one with it.

Nate dog, the bezel that holds the camera lens cover is welded to the frame, so getting that part out is a major operation; you might be able to take the camera out and drill it out with a drill press; that's probably the easiest way I can think of.

That bezel actually goes over the rear glass so even if there was a way to magically dissolve the adhesive holding the rear glass on (and believe me, it's industrial strength), it still wouldn't come off because that camera bezel overlaps it.

So yeah, if I was you I'd just bite the bullet and either try to salvage just the glass from the lens you bought or go ahead and buy just the glass this time. You're just looking to make things 10 times harder by trying to replace that bezel just so you don't have to buy a tiny piece of glass.