To create a Nested Prefab using a new Prefab, go to the Prefab View of the Prefab in which you wish to include another Prefab. Then select the Objects that will compose the Nested Prefab, right-click and click on
Make prefab. Then, save the Prefab and the change will take effect on all of its Instances. Additionally, the newly created Prefab will generate its Prefab Asset and can also be used as any other Prefab.