Is it possible to have the expand icon there regardless of the screen width.
So the client can expand and show the modal at any time.
No - sorry. There was a thread about this the other day which I now can't find of course. Responsive will only show the details controls when data is reduced on screen. You'd need to use a click event on your own show icon. This is how it can be done with child rows. For a modal you'd need to do something like creating a div and showing it. The modal Responsive uses with DataTables styling is not available via a public API.
Here it is.
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