Fixing back of the phone

Hi Alex-cmps,

The following Apple Support page has a “Get an Estimate” tool that will provide an estimate for repair costs: iPhone Repair & Service - Apple Support. You can also contact Apple Support from that page.

Hope this helps!

If you are in the US it will cost $349 for the back glass of an iPhone 12. If the cameras are also broken, they may just offer you an Out of Warranty replacement for about 60% of the cost of the phone when it was new.

See this link --> iPhone Repair & Service - Apple Support

Whether you think it's worth that much money to repair a phone which is now 3 generations old, only you can decide. If it were me, I'd be more inclined to buy a new iPhone.