This feature is related to Audio Conferencing settings.
You need to assign an Audio Conferencing license for users in Microsoft 365 admin center first. Then, configure the conference settings.
Please note that if Microsoft does not appear initially in the list as an audio conferencing provider after you assign the license, either log out of the admin center or press Ctrl+F5 to refresh the browser window.
For more information about how to manage this settings, please refer to this article: https://learn.microsoft.com/en-us/microsoftteams/manage-the-audio-conferencing-settings-for-my-organization-in-teams.