iPhone Xs max water damage seal

My iPhone Xs max was recently water damaged. Previously the iPhone had been dropped in a lake for 30 minutes and did not receive any damage at all. I had the earpiece speaker replaced and then my iPhone was splashed and was totally ruined. I was told by a different repair person there is a waterproof seal in the phone and when it was repaired the repairman did not replace the waterproof seal. Is this true?

The repairman says he will replace my phone but he wants me to pay for a screen replacement on the broken phone even though it was just water damaged.

Can anyone tell me if there is some form of waterproof seal on the original phone?