@katty3333i My vet does this. They call them "happy visits". You can either schedule an actual "exam" that's just taking the dog to the back to be showered with treats (it's not free bc the staff gives their attention solely to you and the dog)
Or
You can just walk into the clinic and not go into the back and give them treats yourself and whoever is up front and/or free at the moment can pop out and say hi.
That said, I'm sure that whatever vet you have would be willing to charge you the minimum office fee (for basically having their staff section out a block of time just for you) to walk around the areas where the dog would normally go and do some basic exam type stuff to work on positive reinforcement. Actually, if any vet refused I'd question their integrity.
Edit: the minimum office fee at my vet is around 30 bucks, like just to be seen with no diagnostics. Very affordable for what is basically a 30 minute training session. But in these instances it's the actual vet that comes in with you - the person that would normally be the main one doing the scary stuff like aspirating a growth or giving an ultrasound/x ray.