Does Apple replace your iPhone or just fix the screen?

The screen on my iPhone is cracked, everything else works fine and I have Apple care plus. Will they replace the whole phone or just fix the screen? And how long will I be without my phone if they do fix the screen?

It depends on how the screen cracked, they have rules of their warranty

If you dropped it and the screen broke, it is not covered under warranty. Your home insurance may cover it.