Can a three-year-old carry his baby sibling?

I’m researching for my story, so this question is tailored to fiction..

I did my bit of google search on gross motor movement but couldn’t find the one that was relevant, e.g. three-year-olds can ride tricycle, hold crayons, carry a heavy bucket of water without spilling, etc.

I’m not familiar with children, but I’ve seen three-year-olds help carry groceries too. Would a three-year-old be able to hold a baby? If not at age three, at what age can he safely hold a baby?

Thank you so much for any help!