lobsterghost1 made a great response. To add on, your iPhone’s camera lens are made out of Sapphire Glass which is already very durable and on the Mohs scale is a 9/10, right behind diamond. That is the mineral hardness scale. It is hard enough to scratch as it is.
Do not use a camera lens protector, it will negatively affect the quality of your photos. Instead as stated, use a good quality case, and I suggest one with raised ridges around the camera which can help protect the lens from drops and dings. I know for certain that Apple’s cases have that. And also get a good quality screen protector. I currently use Spigen, it was easy to install and the touch is good.