How to expand appbar to show text inside app bar on click of action icon ion flutter?

Question

I am building a app activity which has an app bar which has an icon in the center of the appbar and some text. I want to be able to show the text below t the icon with some transition inside the appbar on click of the icon mentioned before and make it disappear it is already showing.

I tried using sliver but I need the transition to happen with click event not scroll up and down event.