1999 Toyota Corolla water damage to Corolla

Water should not have gotten into the oil because that system is sealed. You can prove that by simply checking the level. Also, you'd have experienced serious engine problems by now. One of the oil's jobs is to "isolate moving internal parts from each other". That's a fancy way of saying "it lubricates" those parts. Water doesn't do that. The engine bearings would fail and you'd hear a loud knocking sound from the engine.

If the air intake was suddenly overwhelmed with water, the engine would have "hydro-locked" and stopped running. The pistons have to be able to compress the air when they move up. Water can't be compressed, so the pistons can't move and the engine stops. You'd have to remove the spark plugs to get the water out, and then there's a good chance no major damage occurred, especially if this happened at a very low engine speed. If the engine is running, there can't be any water in the cylinders.

What I suppose could happen is some water made its way into the air intake system at a slow enough rate to not cause stalling, and it collected in the exhaust system. There it would restrict the free flow of exhaust gases until it fully evaporated. That wouldn't take very long. Beyond that, if the engine is running okay and the Check Engine light isn't on, you might want to have the exhaust system inspected visually for leaks to see if that's the new sound you're hearing.

You misunderstood my meanin'. When the engine gets flooded with excessive water, it will cause the engine to lock up, but usually without causing serious or permanent damage. The engine will not turn over with the starter because there's no way for that water to get out, ... Until you remove the spark plugs. At that point, with the spark plugs removed, cranking the engine just a few revolutions will push the water out. Once the spark plugs are dried off, you can reinstall them and the engine should start and run.

You've been driving for two days. That means if there was any water that got into the air intake system, it has been gone now for two days. If you're having a running problem, it's more likely water got into an electrical connector. If something sounds different, look for a plastic shield that got moved, a leak in the exhaust system. Or a missing noise shield. Noise shields can be a rubber plug in a hole, a plastic or rubber plate or cover, or a rubber tube placed over a hose or bracket. They are there to reduce the chances of you hearing a noise that is normal for that car. Unless you notice something missing that was there before, missing noise shields are hard to spot unless you have another identical car to compare yours to or you're a dealership mechanic who is familiar with that model and recognizes the part is missing.

Very often a dealership mechanic will know exactly what to look for with a specific noise because they've heard it before when they forgot to put something back correctly during some other service.