/usr/share/plasma/look-and-feel/ is in kubuntu-settings-desktop 1:18.04ubuntu11.
This file is owned by root:root, with mode 0o755.
..
/usr/share/plasma/look-and-feel/org.kubuntu.desktop/
/usr/share/plasma/look-and-feel/org.kubuntu.desktop/contents/
/usr/share/plasma/look-and-feel/org.kubuntu.desktop/contents/defaults
/usr/share/plasma/look-and-feel/org.kubuntu.desktop/contents/layouts/
/usr/share/plasma/look-and-feel/org.kubuntu.desktop/contents/layouts/org.kde.plasma.desktop-layout.js
/usr/share/plasma/look-and-feel/org.kubuntu.desktop/contents/previews/
/usr/share/plasma/look-and-feel/org.kubuntu.desktop/contents/previews/fullscreenpreview.jpg
/usr/share/plasma/look-and-feel/org.kubuntu.desktop/contents/previews/preview.png
/usr/share/plasma/look-and-feel/org.kubuntu.desktop/metadata.desktop
/usr/share/plasma/look-and-feel/org.kubuntu.desktop/metadata.json