Is this a weed?
I think it is Amaranthus cruentus, definitely a garden plant and one you could eat. In Mexico, it is called huautli and alegría and in English it has several common names, including Blood amaranth, Red amaranth, Purple amaranth, Prince’s feather, and Mexican grain amaranth.
Weed = plant where it is unwanted. This one looks pretty! I’d say not a weed 🙂