Water resistant, not water proof, and resistance may decrease with age and other factors.
The SIM tray has been reported as a weak point WRT water, so I keep a piece of 1 mil polyamide tape over it for extra ‘insurance’, electrical tape would do as well. I use a case so it isn’t a cosmetic issue. And since I charge wirelessly most of the time, I keep a plastic port plug in the lightning port to keep pocket lint and maybe water out of it if I am unfortunate. You can get a lifetime supply of these plugs on Amazon for about $5 I think. As you might think, I’m an ‘ounce of prevention’ kind of fellow.
You might make sure that the lightning port is clean/free of debris/lint.