Microsoft To Do


Tasks assigned to you in plan appear in Microsoft To Do under the Assigned to me option.  



Microsoft Outlook


By default, tasks assigned in a plan do not appear in the Outlook task list.


You can get around this limitation using a Power Automate template called Create a task in Outlook Tasks when a Planner task is assigned to me.  Note that the template only creates a task, it doesn't update it over time or register when it is completed.