The Manage Calendars permission is required to reschedule and amend Calendar Tasks and Appointments. This permission will also allow you to reschedule Reviews for Learners that are not part of your Caseload.
Following the January 2023 Product Update, It is now possible to reschedule an 'In progress' Review - one that has already been started. To do this, administrators with the 'Advanced Delivery Management (Edit)' and / or 'Supervisor' permissions can edit the Review from the Reviews grid 'Planned' tab, or use the Scheduling Assistant on the Reviews grid, or the new scheduling user interface (UI). A reason for rescheduling can also be entered.