Using custom Tags with Microsoft Teams
A tag can be added to a person on a specific team. After you have added a tag, it can be used in @mentions in any standard channel of the team.
NOTE: Tags are not yet supported in private channels.
Manage tags settings for a team By Default team owners can set whether members can add tags at the team level. To do this, on the Settings tab for a team, go to Tags, and then choose who can add tags.