Planner Folder

unfortunately, you currently can't organize plans into different folders in Microsoft Planner. However, this is a feature that many users have requested, and the Microsoft team is considering adding it in a future update.

If you would like to you can send a feedback request to Microsoft in Microsoft Planner:

- Click the Settings icon

- Under "Planner" click "Send Planner feedback".

- This opens "Send Feedback to Microsoft"

- Click on "I have a suggestion" 

As a small workaround you can use tags to organize your plans. Tags are a great way to group plans together based on different criteria, such as dates, types, or projects. To add a tag to a plan, simply type the tag name into the "Tags" field when you are creating or editing the plan.

Flag your tasks with labels - Microsoft Support