Replacing Camera Lens? (i6s)

I just bought an iphone 6s (coming from an Honor 8) that had a shattered camera lens and took it straight to the apple store to replace the battery and get a new lens. When I was at the genius bar I was told that they can't replace the camera lens. The phone can still take photos but they come out blurry, what can I do to replace the lens? Manually do it myself?