Possibility to know the estimated duration of an activity

Is there any way to know the estimated duration in hours for an activity without creating a WO for it?   If an activity has 3 operations and 2 resources in each operation for let's say 2 hours each, these resources may be scheduled sequentially /parallel and the operations may be networked or may be independent.

We would like to know how many hours will be scheduled for the activity to be completed when it is converted to a WO.