This is can be achieved also with a simple list view and a boolean per list view which can be toggled true/false to show or hide the item.
Add in your page a ‘openened’ element which is visible when the boolean is true.
Add another element in your page for ‘closed’ state of the item and make it visible when boolean is false.
In this way you have way more flexibility then a groupbox.
Try the acordion widget https://marketplace.mendix.com/link/component/117895