I grew up with a pedigree dobermann from the age 3 months, pup was 2 months.
I've grown up around large breeds & not one had ever been an issue.
My DH has kelpie x blue heeler, had her before we met & she is an almost 13 year old grumpy, nasty thing & I worry every time DS goes outside. She has apparently been like that since birth!
The other dog is a 2 year old staffy x with who knows what. We got her when DS was about 6 months, she was 2 months & they've grown up together so far. She is the most adorable, soft centered creature & so tolerant of DS & his draping himself over her for a cuddle. They walk around the back yard together & are the best of mates.
But, I still would not trust her or DS for that matter 100%. You just never know.
She was a rescue dog along with her 7 siblings.
A friend had a pedigree blue heeler & although he was very dominant, was amazing with her babies & also as they grew.
A lot is teaching the kids how to respect the dogs.
It will also depend on your room, as in back yard or whether you want an inside dog too.
Food & vet bills are also something to consider.
All the best. It is such a great addition to the family.