What if my iPhone 11 is regularly submerged in water?

It should not be submerged in water for any reason, much less regularly. It is not waterproof.

You will destroy it, if you submerge it in water. Water damage is not covered by the warranty.

Read here: About splash, water, and dust resistance of iPhone 7 and later - Apple Support

Sooner or later, you will destroy it.

It is NOT waterproof.

You should NEVER intentionally submerge it.

You might get some insight from this: Understanding Water Resistance

It will be ruined and become useless.