I work with GitLab, where I often have to create Merge Requests. You can do this using the browser based graphical user interface, or from the command line when doing a git push: You can specify several push options for merge requests via the argument -o:

• merge_request.create: Create a new merge request for the pushed branch.
• merge_request.target=<branch_name>: Set the target of the merge request to a particular branch.
• merge_request.merge_when_pipeline_succeeds: Set the merge request to merge when its pipeline succeeds.
• merge_request.remove_source_branch: Set the merge request to remove the source branch when it’s merged.

There are many more.

I have a git alias to push my branch and create a merge request at the same time:

[alias]
	mwp = "!f() { git push
	-o merge_request.create
	-o merge_request.remove_source_branch
	-o merge_request.target=\"$(git rev-parse --abbrev-ref '@{u}' | cut -d/ -f2)\";};f"

With that my workflow looks like this:

$ git fetch origin
$ git checkout -b feature/foo --track=inherit main
$ # hack away
$ git add …
$ git commit …
$ git mwp origin

The last command will push my local branch feature/foo to the remote named origin as a new branch with the same name . It will also create a merge request (using the first commit as description), which will target main.