"planned to be completed" of epic and stoy

Hi,

I usually use process template "scram".

Regarding work item "task", we can specify the estimation how long it takes to complete it.
But regarding epic and story, there is no such attribute.

In plan editor, there is Planned Time view.

In that view, we can can control when the work item is completed.

I sorted the work items in various order in the view.
Then it seemed that story was estimated to be complated within one day and
epic was estimated to be complated with spending no time.

So I got a question how story and epic are estimated to be complated.

Please let me know about it.