If the delegates of the ListView is what you looking for, so you can set the list size from the delegate:
ListView {
    id: myList
    width: implicitWidth
    height: implicitHeight
    delegate: Component {
        Rectangle {
            width: _col.width; height: _col.height
            onHeightChanged: myList.height = Math.max(myList.height, height);
            onWidthChanged: myList.width = Math.max(myList.width, width);
            Column {
                id: _col
                Text: "Salam :)"
            }
        }
    }
}
This approach is more meaningful when delegates are same size and you can limit the calculation with first item (index === 0)