Unlike actions and fields, exposed states cannot be rearranged in the plugin editor - i.e. they do not have “move up/down” buttons. As a result, they appear in the Bubble editor UI - i.e. in the expression builder - in the order in which they were defined.
However, it might be desirable to have them to appear in a specific (more “logical”) predefined order. If you use the GitHub sync feature, you can accomplish that by simply rearranging them in the params.json file at the root of that element’s folder.
Interestingly, they will not appear in the new order within the plugin editor itself, but they do appear in the desired order in the expression builder of the Bubble editor.