As the other poster said, could be either.
If you do NOT want it left on the doorstep, put a sign on your door saying Please do not "safe drop" or something to let the postal worker know you would rather have a collection card.
If you DO want the item left (and the postal worker is permitted to leave items) you can leave a sign that says you would like it left there, maybe behind the planter or in the barbeque.
Keep in mind that if the item is left and someone eyes it in passing and sneaks up and steals it, you will not be able to file a claim for refund because the tracking will say it was DELIVERED.