How can I change the main branch in a repo programatically?

[Garreth McDaid]

I need to change the main branch in about 50 repos in Cloud Bitbucket. I know how to do this via the UI, but is there a way I can do it via the Cloud API, or using git?

This answer https://community.atlassian.com/t5/Bitbucket-questions/How-to-change-MAIN-branch-in-BitBucket/qaq-p/312366 has been posted before, but it isn't correct.

The git commands there will only change the default branch in the local repo, not in the Bitbucket remote.