Please reconsider using a harness with the leash attached to that the ring. The reason is because IF leash is attached to the collar, it concentrates all that dog’s power as unnecessary strain on the neck, which is very delicate, and over long-term this can lead to issues which may very well result in surgery by a vet.
All the harnesses (even different models within the same manufacturer brand) fit very differently. If you go to an independent pet store, often they will allow or even help you try them on to get the right fit. Or you can order many online to try and keep what works.
To give your dog more freedom, you may want to consider using a longer lead line. There are 30 feet and if even 50 feet leads available. People who advocate against using retractable are not fascists & it’s not about power/freedom. It’s about keeping the dog and the walker safe. Retractable leashes are well known for snapping among the components, and then that retractable which coils up can hit the walker in the eye or face, or it can hit the dog, or if the dog pulls too hard the retractable can slip out of the hand, fly through the air and hit the dog. In those circumstances, it often means that you’ve basically got an unleashed dog that’s no longer attached to a human and can end up being one of the statistics of dogs that never return home before some sad fate befalls them. Also it’s well known that the retractable leashes if they get wound around the dog or the human, the cord/ribbon can burn through the skin. Depending on where a dog is walked,a retractable or even a very long leash doesn’t protect dogs from dangers. In my area there are coyotes, less frequently mountain lions&bobcats, birds of prey, vehicular traffic, bees and other dangers of nature.
It’s akin to a loving parent not giving a baby or young child the “freedom” to put their hand in am electrical outlet, socket, or hot stove, etc.