my iphone 6plus got soaked in water and now battery is low but won't accept the charger plug in.
Is the iphone ruined or will it work eventually once it dries out?
iPhone 6s Plus, iOS 14
99% chance it's ruined.
Leave it a couple of days. If it fires up, back up what you can and back up regularly.
Backup and restore (using the computer method preferably)
How to back up your iPhone, iPad, and iPod touch – Apple Support