Default project configuation - add new branch automatically

Hi everyone,

I’m new in GitLab and need some help.
I want the following:
1.) A new branch “dev” should be created
2.) The new branch “dev” should be the new default branch. The branch “main” will not be deleted and still exits
3.) For every new project, that should be created, the steps 1.) und 2.) will run.

Is this possible to configure in GitLab?

My GitLab is Self-Managed.