By default, Exchange Online allows other users in your tenant to see limited details of your availability when scheduling meetings. More information can be displayed by updating the calendar permissions for mailboxes. This is easy to do with PowerShell, but needs to be done on an ongoing basis because Exchange Online doesn’t have an organization or mailbox plan setting to assign the value to new mailboxes.
https://office365itpros.com/2021/09/21/allow-other-office365-users-see-calendar-availability/
