No iPhone is water proof - see About splash, water, and dust resistance of iPhone 7 and later - Apple Support
Water damage also voids your warranty, so repair fees will apply. The warranty is not valid because the terms explicitly say it isn’t - water damage voids it. Those terms are the same for all IP67 and IP68 rated smart phones, from any manufacturer.
A water resistance rating is not a guarantee against water damage. It merely means a rated device is less likely to be damaged than a non-rated device would be. And nothing about the IP67 or IP68 rating indicates a device is suitable for actual use underwater. The rating test is carried out in a laboratory, in pure clean fresh standing water. The device is not used nor even moved during the test.