Case or no case, if a phone is dropped on a hard surface, it's pretty much all glass and glass can crack.
Is it the front screen or both the front screen and back glass?
If just the front screen, you can have Apple install a new screen at your cost as accidental damage is not covered under warranty. If the front and back of the phone are damaged, it will require the entire phone to be replaced as the back glass on iPhone is fused and cannot be replaced.
If just the screen see this link for pricing --> iPhone Screen Repair & Replacement - Official Apple Support
If both the front and back see this link for pricing --> iPhone Repair - Official Apple Support