MS Planner: View tasks on a calendar
In Microsoft Planner, once your task has a start or due date, you can see it on a calendar either in Planner using Schedule view or in Outlook by adding your plan to your Outlook calendar.
Use Schedule view to see tasks on a calendar
After you add tasks in the Board view of Planner, you can see those that have start or due dates by choosing Schedule at the top of your plan.
You can then grab the right end of any task to stretch it over two or more days.