People with admin or owner permissions can set up a CODEOWNERS file in a repository.
The people you choose as code owners must have read permissions for the repository. When the code owner is a team, that team must be visible and it must have write permissions, even if all the individual members of the team already have write permissions directly, through organization membership, or through another team membership.
About code owners
Code owners are automatically requested for review when someone opens a pull request that modifies code that they own. Code owners are not automatically requested to review draft pull requests. For more information about draft pull requests, see "About pull requests." When you mark a draft pull request as ready for review, code owners are automatically notified. If you convert a pull request to a draft, people who are already subscribed to notifications are not automatically unsubscribed. For more information, see "