When I'm in sheet view, and I have no filter active, I can see little arrow to collapse/show all cards. That allows me to see all the child cards that are sorted underneath a parent card.
When I activate a filter (status > filtering out all 'recurring/repository' cards), I don't see the arrows and the hierarchy of the parent vs child cards anymore.
I'll describe shortly how I particularly use this.
I use the kanban view on most days. When I plan my sprint at the beginning of the week, I drag in stuff from my backlog. That makes it messy and requires cleanup - so I go in sheet view, and assign some cards to parent cards.
Then I can easily see the big picture.
I suspect I am using it wrong, or can use another feature for this though... Suggestions welcome. Ideally, I'd like to see some sort of hierarchy in kanban view as well, but all I know so far are dependencies. Might be useful to use sub-boards or smth like that, but unaware of other features that provide the capabilities I need so far.