The answer is a solid "it depends".
While Liferay support Hot-Deployment of modules, I rarely see that done.
If you're running containerized, typically a new image is built and
deployed to the runtime environment, while the old one is torn down.
If there's no upgrade required in between, that can happen without downtime.
How you synchronize your deployments to the same time is up to you
and depends solidly on your environment and how much / how you've
automated its operation. From Liferay's side there's no magic and on
the level of your question nothing is either CE or DXP-specific.
