Should a feature branch of forked repository ever be merged to origin main?

Let's consider, 3 people are working in a project and they are using git. Can the project repository be in any one of their github accounts. Or is it more convenient to host the remote project repository in a new account?

Now, one of them will work on a feature. So, he will fork the repository, clone it, git, create feature branch, make commits in the feature branch and then git push origin feature. Then, create a merge request from github site
Then, what should he do?
Should he merge origin feature branch to origin main? Or delete the feature branch? Or keep it untouched? Should any commit be made in the feature branch after the merge request is accepted and closed.

At a more broad level, the question is:
What does workflow look like(what are the conventional steps) when using git in a team project? What is a complete Gitflow cycle?

Note: Please feel free to edit the question, if u think it is not framed correctly. Also help, if what steps I have enumerated is wrong or some pieces are missing.

Solution 1:

With Git (and even more with Git + Github) you have a lot of possible workflows for team-based developments, you have to define applicable and usable for your team: everybody have own habits and mileage may|have vary

You can:

• Use single repo or forks
• Use personal repo and add collaborators to it or have "organization" + "org. repo" + "org. members"
• Use PR (pure GitHub specific) or enable just merge branches
• Use GitFlow or GitHubFlow or Trunk-based develpment or ...