Have a look here first …
You set up your text within a “stretch to fit” text box, which is inside a Collapsible Group. When you click something, you show the group, and the repeating group expands.
However, I am not sure that you can do a “hover” condition to trigger this. But there is another way with hover that might work.
You need to put the text, set to “stretch to fit” in a text box, but set to truncate at the first x characters. Make this fit into your cell. You then have a condition set to hover that changes the Text, and pull back ALL of the text you want to display. This will also make the repeat group cell expand.
So it isn’t quite as you wanted i.e. you wouldn’t be able to hover an icon and make the text box expand. But maybe near enough ?