Want to download python3.6.x but don't know how

I could only find anaconda with python3.12 for windows now, where can I find anaconda packs with previous python versions?

You can search the release notes for which version of the Distribution installer has the version of Python you want: https://docs.anaconda.com/anaconda/release-notes/
Older Anaconda Distribution installers are available in the archive: Index of /
Miniconda installers are available here: Index of /
More details in the documentation: Using older versions of Anaconda Distribution — Anaconda documentation

Also, you can install the latest version - and create an environment with an older version of Python. Docs on using conda environments: Environments — Anaconda documentation

Hope this helps!