Thank for your reply. I deleted from Netflix app on iPhone. The downloads deleted on Netflix app do show up as occupying space on Settings > General > Storage. When I select EDIT, the circles that appear next to the items cannot be checked to be deleted.
Thank you for your suggestion. The downloads deleted in the Netflix app were indeed occupying space in my iPhone. But I discovered by chance that when swiping the item to the left, a red DELETE box appeared. Problem solved!