If you end up rounding off the head there are a few options. They make special sockets that can grab onto a rounded off bolt. You can try to hammer on a slightly smaller socket. You could drill the head off of the bolt and use an extractor to pull the remnants out, but you risk breaking off the extractor and then you're in a real pickle. You could also weld a nut onto the bolt, but not recommended with a full oil pan. You can also take a hammer and chisel and try to get the bolt to turn using it at an angle, not recommended if you have an aluminum oil pan. You could also just buy an oil extractor and pull the oil through the dipstick tube.

In my case I had rounded off the bolt head in a few spots with an open ended wrench after a few tries not realizing it was going to be stubborn. Had a hard time getting the correct sized close ended wrench on with the warped sides. Went up a size by switching to metric and getting a decently good grip. That stripped it further, but warped the head even more so I was able to get the right sized closed wrench on it with a few "gentle" taps of a hammer. It juuuuuuust barely came off. The head was mutilated to hell.

I've seen people use a grinder to grind down the sides of the head and use a smaller wrench to try again. Or cut a plus in the head and try a screwdriver. But that's assuming the head hasn't popped off yet.

Impact driver, but the bolt could snap.

Actual oil pan bolt torque is lower than people think, but a fresh crush washer should be used every time.

Now Fords use plastic oil pans, which should be fun with those gorillas.