The worst thing you can do is to try and power on a visibly wet device. This is followed closely by Rice because it does nothing but gives you the illusion that it may be helpful while letting corrosion damage the logic board. The next worst thing you can do is to do nothing...but at least you don't have any false illusions
.
Seriously, if you care about the data or the phone, get it to a shop that specializes in water damage/data recovery. They will have the proper tools (ultrasonic bath) and skills (micro-soldering) to "maybe" revive the phone or at least get your data.
If you can't do that, then open the device, remove the logic board, remove the shields (if you can - some are cloth) and put the logic board in some >90% pure IPA and let it soak; this will help to displace the water. Brush away any visible corrosion and then let it air dry; if your fortunate, this may be enough. If this does work, then get the data while you can because you never know how long a water damaged phone will last.