Hi Nomad Bee,
The cracked lens isn't as big of a deal as you might think. The thing is, all it is, is a piece of glass glued to the camera bezel, so fixing it is really just a matter of prying the old glass out and gluing down a new piece.
While there aren't any guides for that repair made for your phone, in reality it's the same for pretty much every phone out there. I've done this exact same procedure on a Pixel 2XL and an iPhone 11 Pro Max. Here's a guide made for a Pixel 2 that will tell you everything you need to know.
[guide|136980|Google Pixel 2 Rear Camera Lens Glass Replacement - iFixit Repair Guide]
The glass itself is easy to come by; just search for iPhone 13 camera lens replacement and you'll get plenty of choices, including places like AliExpress, Amazon, Temu and others. Here's just the first one that came up.
[link|https://www.aliexpress.us/item/3256805591340725.html|NEW Tested For IPhone 13 Pro Max 13mini 14 Plus 6s Camera Glass Lens Back Rear Camera Glass Lens with Glue Replacement Repair - AliExpress 509]