Just buy the most aggressive dog possible and learn by doing. Practice >>> theory

I found this video super helpful in training my dog to walk beside me. I’m not sure the quality of his other videos but he gets good reviews. https://youtu.be/J0FxFlnmSR8?si=RaURCeHEayyjILA2

A Dog in Hand is a good book to read on raising a puppy. https://www.goodreads.com/book/show/1278930.A_Dog_in_Hand