Oh, I read it wrong - "How do I shrink the scroll to behavior screen size" :)
You need to use a different "camera" object for Scroll To behavior (remove it from the character). Normally the camera will follow your character, but when you don't want players to see past some area, you need to stop the camera at some distance from it.
For example, to enable scrolling only between 1000 and 5000px:
On every tick -> Camera set X to clamp(character.X, 1000, 5000)