Filtering and sorting are currently only available in ClickUp Views. However, when multiple tasks are connected through a Relationship field, there is no way to filter or sort the related tasks directly inside the task.
The only workaround is to create a separate View and filter it using the Relationship field. This defeats much of the purpose of displaying a related list of tasks inside the task record in the first place.
Please add the ability to filter and sort related tasks directly within the Relationship field. This would make it much easier to work with large numbers of connected tasks without having to leave the task and create a separate View.