The type of elements created in the designer can never be changed outside of the editor. ie you can’t change a button to a textfield or a panel to a horizontal box.
Checking “is variable” just makes it appear at all in the variables list- which you can then interact with in the blueprint editor.
There is no way to enable the eye icon (to make it Instance Editable) with widget components- though you can with regular variables that aren’t components.
That data simply cannot be edited directly from the editor at runtime- which is the purpose of being instance editable.