My phone has been dropped in the pool and now it is a black screen but I can still hear vibration and sound!

No, water damage is not fixable. You can turn it off and not use it or charge it for a week or so; there’s a slight chance it will recover once it dries out. But if it doesn’t Apple will replace it for a flat fee that will be less than a new phone→iPhone Repair - Official Apple Support

Dry it for a week or so without using or charging it, using moving dry air, and in a dry environment. In an air-conditioned space, for instance. (Not in rice. Rice dust and rice debris getting inside an iPhone won’t do your iPhone any favors.)

The iPhone might work after prolonged drying, or it might not. It might or will corrode over time.

About splash, water, and dust resistance of iPhone 7 and later - Apple Support (includes Apple’s drying suggestions)

Water and other liquid damage to iPhone or iPod isn't covered by warranty - Apple Support

Not a good idea; it can blow the water deeper into the phone. A dry environment, and as MrHoffman pointed out, not rice. You can use Silica Gel if you know what you are doing, but only use a canister of silica gel that won’t emit dust that might get into the phone→https://www.amazon.com/Indicating-Desiccant-Canister-Dehumidifier-Reusable/dp/B07Z8ZYJ75/ref=sr_1_20?crid=G9HRTA392HDZ&dchild=1&keywords=silica+gel+packs&qid=1632065699&sprefix=silica%2Caps%2C177&sr=8-20