What happens if my phone gets wet and dried well?

As @danj suggests, using rice to dry the inside of a phone is little more than a myth and should be avoided at all costs. As for the iPhone 7, it is water resistant but keep in mind that Apple does not warranty it as water resistant. If it is damaged by water, you will pay the full OOW replacement cost. I guess that tells you how much Apple trusts their water resistance.

iFixit famously tested an iPhone 7 in an aquarium and it lasted 8 hours. However, recently there have been similar questions to yours where the phones only took a quick dip in water and still failed. It really depends on the individual phone, the type of water and circumstance. In a perfect world, you should have it decontaminated. Better to spend 30-50$ to be certain everything is clean inside than to have to pay >300$ to replace it in a few months because corrosion was eating away inside.