Vizslas are not aggressive, but that doesn’t mean that they can’t be intimidating.
If it were me, and remember that he is your dog, not mine, the first thing that would stop is getting on the couch, or furniture. Move his crate into the same room, but he earns that privilege of being on the couch.
The second thing I would do is desensitize home to food. With my dogs, I put food, or treats in their bowl, and then put my hand in the bowl. They have to eat around my fingers. With bones, and maybe scraps of meat. They eat it, or chew on it while I hold it. I take it away and give it back repeatedly. Over and over again. They get assertive, it’s removed, and a stern warning given, then repeat. They always get it in the end, but it is on my terms, not theirs.
He growls at your child, you go absolutely ballistic on him. He’s big enough that he can take a firm correction, and then he should be put away for a time out. You’re not trying to beat him here, or hurt him. It is a very quick physical correction, with a lot of threatening tone, and then it is over. We’re talking 5-10 seconds. Put him in his crate for a time out, then let him out, and work on social skills.
There is absolutely nothing wrong with him keeping a 3’ length of leash attached in the house. This way, if he gets unruly, you need to only get ahold of the leash to regain control, not deal with him being snappy.
He’s looking for a leader to tell him what to do.
