how can change default branch in github code example

Example 1: change git default branch

git config --global init.defaultBranch <defaultBranchName>

Example 2: change default branch github

On GitHub, navigate to the main page of the repository.
Under your repository name, click Settings.
In the left menu, click Branches.
Under "Default branch", to the right of the default branch name, click .
Use the drop-down, then click a branch name.
Click Update.