//No Kotlin, Java only
Create two expanded cardViews under each other using relative layout, if you expand one card, the other one should collapse. make it possible to show one card, both, or hide both. add observable fields to monitor the state of the card: opened, visible etc.. the whole card should be clickable to expand not only when you press the arrow.
//All views should be native Android, not extra libraries
//default transition animation
example attached below