Does your dog pull and get overly excited when they see other dogs or people? Do they bark at other dogs while on leash?
If you answered yes to any of the above, you may want to work on your dog’s impulse control.
I do NOT ADVISE you allow your dog MEET other DOGS on leash for these reasons:
if you let your dog run up to every dog to greet them while on leash, they are going to learn that this is an acceptable behaviour and they are going to want to pull towards every dog they see
DOGS GREETING FACE TO FACE IS A NO NO!!!
TRY INSTEAD: identify at what distance your dog notices other dogs or triggers - and try to catch them before that distance and have them perform an alternative behaviour (i.e. sit. look back) give them a treat - check out this video to teach your dog the “look back” game to help with on leash impulse control
if your dog has already caught whiff of the other dog before you can get them to calmly perform an alternative behaviour, then redirect them and walk the other way
On leash reactivity is very common and some dogs feel vulnerable while on leash (wouldn’t you if you were tied to somebody and couldn’t escape if something scary was coming your way). If you let your dog run up to another dog and jump on their face - firstly, it is not the right way to greet another dog, secondly the other dog may have on leash reactivity and not take too well to being pawed in the face
TRY INSTEAD: reward your dog every time your dog goes to sniff another dogs rear end first (it’s how does identify each other) ** mind you don’t let them linger there - a couple second sniff is appropriate, staying there and licking is considered rude
Once you are confident your dog is going to say “hi” by sniffing butts, ask the other owner first if your dog can say “hello” - if they can only allow your dog to say hello after they are calm and you give them the command to go ahead and say hello
If your dog is not listening to you or overly excited, there may be underlying reasons: health, under stimulation, stress, etc. Make sure your dog has the right level of mental and physical stimulation, monitor any changes in behaviour/health and think about whether any of the actions you are doing are reinforcing your dog in the WRONG way (i.e. are you encouraging the WRONG behaviours vs the right ones).
Here are some other great resources to read up on leash reactivity and impulse control