Following Git 2.28’s highly sought after ability to configure init.defaultBranch comes GitHub’s support at the platform level.

You can now set the default branch name for newly-created repositories under your username. This setting does not impact any of your existing repositories. Existing repositories will continue to have the same default branch they have now.

But even if you do nothing…

On October 1, 2020, if you haven’t changed the default branch for new repositories for your user, organization, or enterprise, it will automatically change from master to main.