Writing stories with dark, difficult themes and action has been challenging for me sometimes. Yet they can be part of what drives a story forward. I really appreciate the advice given here, and I probably ought to have heeded it myself on more than one occasion.
I understand that a story tag can convey enough warning to a potential reader. However, the tags must be sufficiently general enough to cover plenty of ground, and the treatment of material under dark themed tags can vary widely, from subtle to explicit.
A warning may have some use, as a GA novel may not have the same kind of cover a physical book does. The Story Description becomes the analog of the jacket blurb. It ought to say enough to tell readers what kind of take they’re getting themselves into. Perhaps that’s why publishers have professional jacket-writers; it seems to be an esoteric art form.