Any dog can "turn", if by turn you mean "reach the end of its tether".
Research breeds. Some are more likely to be calm and people-friendly than others. Staffies for instance tend to be lovely with people but not always with other dogs.
It is emphatically NOT all about how they're raised. Genetics play a huge part.
When you've found a breed you think might be a good fit, find a responsible breeder. There is plenty of info online about how to do that/what to look for.
Talk to them. Find out about their dogs. Meet as many of the offspring/previous litters as you can. Ask to speak to owners of previous litters. Find out about how the puppies are raised. Whether they will get to mix in a controlled way with children. Nurture matters too.
My present dog spent loads of time with young teenage girls as a puppy (the breeder had granddaughters who visited often) and even now if she sees groups of girls she wags and wiggles and wants to interact 😄
Be realistic about how much work puppies are. Clue - huge amounts.
It's not like Disney. Interactions with dog/toddler have to be carefully managed. Toddler will need as much training as dog in order to learn to leave the dog alone. Even if you think they're both trained they won't be able to be left alone together unsupervised.
I'd strongly advise you wait.
Me, I managed to time it perfectly so that the day my youngest started school, I waved him off with indecent haste and immediately drove to pick my puppy up 😄