Does apple relplace ur iphone for free for pnly one time

Check Your Service and Support Coverage - https://selfsolve.apple.com/agreementWarrantyDynamic.do - "Review your Apple warranty status and eligibility for support and extended coverage." Requires a hardware serial number.

They will replace it if there is a demonstrated problem that is covered by the warranty.

If they determine it is not covered by warranty and is not obsolete, and is not broken into multiple pieces or other reason to not be eligible for out of warranty replacement, then you would have the option of paying for a refurbished model.

Vintage and obsolete products - https://support.apple.com/HT201624

Edit: Oh, you mean if they don't have your model. I don't know what they do. Maybe they will offer you the next higher model they have available, or maybe they will order your model and you will have to wait. I do not know really.

Apple will help you for free in any manner that is consistent with your AppleCare and/or warranty agreement. Check your coverage here: Check Your Service and Support Coverage - Apple Support

Apple only replaces an iPhone due to warranty issue or a requested Out of Warranty replacement for a fee.

Yes, if they have one.