Amacker patented such an arrangement quite a few years ago. They offer some stands with the feature and so did the Loc-On company at one time. I have a Loc-On Contender that uses it. Worked OK when new but it depends on a bungee cord to pull it back together and those cords get weak with age and need to be replaced. I never have figured out how to replace it.
Might be someone else making them but that's the only truly adjustable one I know of that as you climb you can make it smaller and as you come down you can adjust it out larger.
Any of the climbing stands with cables "can be" adjusted at risk of life and limb when doing it. The Amacker Adjuster mechanism is the only one I'm aware of intended to be done that way.