Hey @Tushar_Kungar, @bkspace is on point, here. There are lots of ways to approach extending/building cart drawers and my understanding is that it’s not currently possible to approach this with theme app extensions directly (more info here)
The most common way folks approach this is using the AJAX Section Rendering API to fetch cart data, create a <div> for a widget, and insert it into the drawer whenever it opens.
There’s a bit more info on this approach here if you’re interested too.
Hope this helps!