No, they do not. There is a common misconception that harnesses cause your dog to pull and that you cannot teach a dog to walk on a loose leash using a harness. This statement is not true. You can teach a dog to walk on a loose leash using any type of equipment.
Maui walks on a loose leash wearing a back clip harness
It is true that some harnesses and equipment do not do anything to prevent your dog from pulling but none actually cause or encourage pulling. The only thing that creates pulling on leash or loose leash walking are consequences. Consequences can be defined as something that happens within 2 seconds of a behavior happening.  When your dog pulls and continues to get to where they are going they will pull more often in the future because pulling is being rewarded. When your dog pulls and you ensure that they do not get to where they want to go you have just prevented pulling from being rewarded and it will happen less often in the future.
These two dogs are showing off the Perfect Fit harness and the Freedom Harness
There are even some harnesses that are designed to prevent and limit pulling like a front clip harness. A front clip is a harness that has a clip in the front, that sits right on your dog’s chest. When a dog is wearing a front clip harness and they pull, it turns their bodies slightly sideways to prevent them from being able to pull.
Charlie walks on a loose leash wearing a front-clip Freedom harness
A front-clip harness will work for most breeds and most sizes of dogs. It is a great tool to help reduce your dog’s pulling. Most dogs adjust to the harness quickly. When your dog pulls the clip in the front gently turns him to the side and slows him down. A “Y” harness is ideal, you should always choose a harness that restricts your dog’s natural gait as little as possible. The whole dog journal did a review of different harnesses and found that they like the Perfect Fit Harness (my favorite as well), the Balance Harness, and the Freedom Harness. They do not recommend the easy walk harness by Petsafe. 
© Leash and Learn 2020
 ABC: Antecedent, Behavior, Consequence. (2020, January 29). Retrieved from https://www.thoughtco.com/abc-antecedent-behavior-and-consequence-3111263
 Miller, P. C. (2020, March 24). The Best Front Clip Dog Harnesses. Retrieved from https://www.whole-dog-journal.com/care/the-best-dog-harnesses/