General question on apt-get update && apt-get upgrade -y

I see this command loads a whole bunch of software packages. Who\How did this package list get created? I am curious to know how this list was created to know the list of all the pre-reqs. This seems to be a thing within the K8s installations about knowing all the pre-reqs yet it seems they are supposed to be known somehow.

Does the exact same list get downloaded if I ran this on CenTOS? What about RHEL? Is there something, somewhere that would help me understand this specific part of the installation process. And then, would it change?

Thank you.