How to copy Plans in Planner

It takes a lot of work to create the perfect project plan. With Planner's copy plan feature, you don't have to create perfect plans from scratch any more. You can create a copy of the plan so you can reuse it, or you can copy individual tasks. This article explains how to copy a plan, and which elements of plans will or will not be copied to the new plan.

https://support.microsoft.com/en-us/office/copy-a-plan-50401e13-a25f-40df-93c6-b608cc28c3d4