May or may not. You open the UDP ports, you get flooded, they block all incoming traffic, and this way or another your assets are not resolvable.
One must distinguish between application layer attacks HTTP/S and UDP, cloud vendors won’t protect you implicitly for network layer attacks unless you purchased such service from them.
So you buy it. I checked the prices at our provider, and it's something like $20+/month extra and they use some HW from https://www.riorey.com/
Far cry from needing $1e6 HW ourselves.
Sure, but if the services are available, you can just purchase as-needed. If the problem never comes up, you're golden.