It's not a placebo, it works if the water hasn't fried anything yet. The rice will draw out the water, which should make it safe to use again. Back when phones had removable batteries, it worked even more. You rip out the battery ASAP then dry it in the rice with no electricity going through it.I can confirm this as well. I revived an ipod back in like 2010 by leaving it in a bowl of rice for like a week. I also did it for a friend around that time too, with one of those early smartphones.
Maybe it's a placebo, I can't say for sure if the rice did the trick or the electrics just dried out from the time. But it won't do you any harm to try it
In 2022, if your phone doesn't have an IP water resistance rating, you're gambling. I don't use Apple products, but any decent brand Android phone is water resistant or waterproof. IDK what this clown bought, but it's likely trash.