Apple

They will either replace the damaged component or replace the phone with a “service replacement”. Service replacements are new or refurbished devices (you can’t tell the difference).

they have spare parts for older models for repair, they will also hold some refurb units for cases involving replacements

you won't get a discount, you can trade it in, but if it's cracked the trade-in value tanks, so it's usually your best bet to repair it before trading it in

i always get apple care because it's a no-brainer