Explanation
Behavior is a parameter of the CoordinatorLayout.LayoutParams. You can set the behavior on an instance of CoordinatorLayout.LayoutParams with setBehavior method.
To get a proper Behavior object that represents the same thing as @string/appbar_scrolling_view_behavior you should create an instance of AppBarLayout.ScrollingViewBehavior.
Example
(this is a cleaned up version of my previous edits to the original answer)
First you will have to get an instance of a child View of your CoordinatorLayout.
Let me get this clear: it is NOT the CoordinatorLayout itself. childView is CoordinatorLayout's child.
//e.g. like this:
val childView: View = findViewById(R.id.child_view)
Assuming the childView is already attached to the CoordinatorLayout (so it already has LayoutParams), you can do:
val params: CoordinatorLayout.LayoutParams = yourView.layoutParams as CoordinatorLayout.LayoutParams
params.behavior = AppBarLayout.ScrollingViewBehavior()
yourView.requestLayout()