Will Apple swap my water damage iPhone with new one?

They will, but not for free.

You will need to pay an out of warranty fee to get it replaced.

If you have Apple Care+ the accidental damage fee under it is substantially lower than the out of warranty replacement fee.

See here for pricing in the U.S.: iPhone Service Pricing - Apple Support

They may offer you a discounted price on another iPhone, but the water-damaged phone is not covered under warranty.

If you have Apple Care+, you will be in a much better position to end up with a replacement phone.

Hi

They will offer you An out of warranty replacement you will need to pay half the cost of a new iPhone.

Cheers

Brian 🇬-1F1E7;