Time estimate on tasks
There is the possibility to insert a time estimate on tasks?
If you're referring to a due time, you can set tasks to dates with times such as "tomorrow @ 2pm" or "ev Fri at 13:20".
If you're referring to a duration or a task, that's unfortunately not possible directly, but you could add labels representing the estimated durations such as @2h or @5h. This would also allow you to easily search for tasks with the same duration simply by searching for the @2h label.