iPhone X exposed to rain

Putting the phone in rice does nothing except get rice stuck in the charging port. It's a myth. You need to take it to a repair shop and see if they can dry it out. The problem you have with water damaged phones is they start corroding immediately and keep corroding until they are cleaned. The problem is you can't get to all of the spaces. Most shops won't work on water damaged phones except to retrieve data because they are most likely going to have more problems. If they do fix it they most likely won't warranty it. If it ever happens again the best thing you can do is turn off the phone and DON'T charge it and take it to a shop immediately. The sooner they can disconnect the battery and get the water out the better chance you have. I hope it helps