Warranty

The basic 1-year Apple warranty does not cover liquid damage. However, if you elected to purchase an AppleCare+ plan with this phone, and it is still active, you may find that you can get a replacement phone at a discounted price.

Regardless, you should stop using this phone and keep it powered-off to prevent any further damage, and then as others have stated, make a Genius Bar appointment at your local Apple Store or Apple Authorized Service Provider to have them take a look and provide you with your options.

There is no guarantee against water intrusion. iPhones since the iPhone 7 are constructed to a standard for water resistance, but make no claims about how long this will last or whether it can take multiple exposures to water. The warranty terms worldwide include terms that liquid damage is not covered, and in any case the device seems like it might be out of warranty anyways.

Backup to a computer after changing the device name ... prevents stomping a good backup if this one is corrupt.

Then see Apple Genius Bar. AppleCare+ makes replacement less painful. Follow Genius personnel instructions about releasing the old device from AppleID and iCloud.

Water is generally not the best thing to mix with electronics. You'll want to have your device repaired at an Apple Store or Apple Authorized Service Center. Start at Get Support