I dropped my iPhone X in about two feet of water in a shallow part of a pool for about thirty seconds. Has it been damaged?

Two hours later and the screen is working fine and the speaker was muffled slightly at first until I played a tone app to see if it would help and now it's no longer muffled when playing music. Since it's water resistant or can be submersed up to 3 ft maximum and I dropped it in 2 ft of water for 30 seconds, could it be fine? Or I let it continue to sit in rice? Should I use other desiccants?

It's fine. It can go deeper than 3 ft for more than 30 minutes and still work fine.

Dry it out all you can, despite the guaranty. It's amazing it works. Sunlight wouldn't hurt either.

You shouldn't have turned the phone on after dropping it in water. All you need do is let it sit overnight and let it dry on its own without applying any heat to it. It will work fine the next morning. I dropped my iPhone 6s in the deep end of the pool and let it dry overnight and it worked fine the next morning. The seal for most of the smart phones is well made to withstand being submersed in water for a short period, but not for a long period. Never turn on the phone right after its been submerged in water because you may cause a short circuit which may damage the phone permanently.