I dunno. It all sounds a little vague.
Aggressive dogs need to be dealt with and dealt with on an individual basis. Some are just mean little shits that are a direct reflection of their owner. Others have, sadly, been mistreated and/or neglected their whole lives but can be handled in the right environment. Some are just mean by nature.
My dog is 15 Lbs of sheer unmitigated idiocy. She will annoy you to death but in the most adorable way. She's hyper and overly friendly but she barks and growls at outside/unknown noises and probably would bite a person if they hurt her.
She also routinely engages in pro-wrestling matches with my 3 year old daughter. Never an injury save a rare unintentional superficial scratch.
On the extremely rare occasion when she gets loose she'll run straight at neighborhood kids and drop her hind end, look down, turn sideways, and practically beg to be petted.