Washing iPhone with fresh water after salt water damage

Hi everyone - today I had my iPhone 8 in a waterproof bag while paddle boarding but the bag seems to have had some water ingress and the screen has lines on it and the speaker was muffled. I am on holiday in a remote area so can’t take it anywhere but immediately turned it off and am waiting for it to dry. I’ve read a couple of posts online about cleaning salt water damage with fresh tap water but wanted to find out if anyone else can confirm that and if so, how? Im going to guess water has got into the phone through a port, button, speaker etc and is now inside. So should I actually flush those with a tap because that sounds super risky but I’m also aware time is ticking. Thanks so much. Can I also confirm how waterproof the 8 is meant to be? Im aware salt water is worse but it really couldn’t have got that wet and i was of the impression neither type of water can get in; salt water is worse long term but any kind of liquid is bad once it’s in and would require the phone to be turned off so I’m a little confused. Thanks!