Yes there is still a chance to salvage a water damaged phone even after it’s been plugged in. However, keep in mind that by plugging it in you are introducing electricity to a board that could have unwanted bridges between components and that can severely damage a device.
Best thing to do would be to disconnect the battery (if possible) and bring it to a repair centre ASAP. Or, if you feel confident enough, try fixing the water damage yourself! Check out this [https://www.youtube.com/watch?v=DsDpALKQjUQ|link] for some more info