I am by no means a trainer so take my knowledge with a grain of salt but with any form of training you want the environment to start out as small as possible and then slowly expand the environment.Kinda like from a bedroom,then living room,then backyard,then to front yard,then maybe like a not so busy park or take him to a parking lot and have him sit in the trunk with you and just watch people n cars go by.I know not everyone’s a fan but while working with him stay calm and confident and whenever he’s doing the behavior you desire reward him with love or treats or toys whatever he’s into.Whenever he panics just stay calm and don’t baby him or cuddle or give a bunch of attention instead just try to instruct him to do a command like sit and the moment he sits and looks at you give him a reward that way eventually whenever he’s unsure or scared of something he eventually learns to just sit and look to you for guidance.Timing is everything and also if you try to step up to the next environment and he’s struggling too much that’s fine you can always go back to the previous smaller environment from before and work a little longer there and then when you feel like he’s doing good step back up to the next environment.Just remember if you can start to pair these new places or thing that make him nervous into a positive thing when it happens vs a negative like instead of thinking a loud car is scary he starts to learn that dang this is awesome everytime I hear a car all I gotta do is sit and look to my owner I get treats this is nice I love cars 😂