You can start your puppy/ dog on a flat collar and lead
Loose leash walking is achieved through time via 'focus exercises' that you'll need to practice often with your dog, rewarding your dog whenever it walks close to you, teaching your dog to 'look at you' in the presence of distractions...stop moving forward whenever your dog pulls towards something.
Some dogs do well on a collar/ lead while others may do better on a walking harness.
And even the walking harness can be used as a management tool for a while and then after a period of time and teaching- guiding - your dog can move to a flat collar and leash.
Any equipment needs to be fitted properly in the dog.
Never ever use aversive tools in your dog:
- prong collars
- choke chains
- shock collars