Button design: Is there a selected state?

The options for interactions are: regular, hover and disabled
But how do I make a button a selected state?

I can assume that selected state could also be interpreted as clicked, we have such feature in beta now.
please check this article to see some more information on this: https://support.wix.com/en/article/editor-x-about-click-and-hover-interactions-beta
as for example, once the button was selected it moved for a few pixels, once it was unselected by additional click, it moved back to the initial position:

Yes, selected state meaning it has been clicked.
Your example shows the same state after but just moving it.

Is it possible to have an ‘clicked’ state (change colour of button) by using interactions?

hi, @hueofblue yes this is possible, please see the video example
but kindly note that this feature is in the beta at this point