How to find future (planned) versions of Docker?
I'll assume you're talking about Docker Engine for Linux.
Docker doesn't plan releases like that currently. What they do is:
Release major and minor versions on GitHub: https://github.com/moby/moby/releases
Put release notes in their docs: https://docs.docker.com/engine/release-notes
The version number is date based on the month they begin the release process, so the current version &quot;20.10&quot; started its release process in October, 2020 and was eventually released in December, 2020. The last major release before that was 19.03.
Finally, you can see what they are working on (features) and what's next on their Roadmap https://github.com/docker/roadmap/projects/1