Character picking up box

Hey guys, so I've been learning unity but something I can't figure out for the life of me, if I have a 3D animated model which bends down and "picks up" something, how would i go about attaching a box model to its hands?

• Would transform.parent be used? If so, the scaling issue is obnoxious

• How to attach it to the "hands" of the model

Thanks, I really appreciate because I can't find any documentation on it and the search terms are pretty ambiguous