Often OKRs are used every quarter, with just the Key Result target value updated.
You can copy an OKR to the next Quarter or Year by continuing it, so that you can easily see the history of it through time.
Click on the Continue OKR in Next Period in the menu in the details page or on Continue OKR & Child OKRs in Next Period the OKR list or hierarchical view.
OKR Details Page
OKR List View
The list view has a multi-select option as well.
OKR Hierarchy
Options allow you to copy all Child OKRs and Linked To-dos to the new OKR.