kde plasma: set kde theme from a command line in a distrobox

List current themes:

lookandfeeltool -list
can return

org.kde.breeze.desktop
org.kde.breezedark.desktop
org.kde.breezetwilight.desktop
then

lookandfeeltool -a org.kde.breezedark.desktop

More at: https://askubuntu.com/a/1183309