You can ask a seller to cancel your order, but they do not have to oblige.
If you receive no confirmation that the seller has cancelled and a refund is on its way, then the seller hasn't cancelled and sent the item.
If the seller has a Returns Accepted on their listing, when you receive the item, you'll be able to return it for a full refund, but will need to pay for the fully tracked return postage.
@antnnad_2