/usr/share/plasma/ is in kubuntu-settings-desktop 1:18.04ubuntu11.
This file is owned by root:root, with mode 0o755.
..
/usr/share/plasma/desktoptheme/
/usr/share/plasma/desktoptheme/kubuntu/
/usr/share/plasma/desktoptheme/kubuntu/colors
/usr/share/plasma/desktoptheme/kubuntu/icons/
/usr/share/plasma/desktoptheme/kubuntu/icons/start.svgz
/usr/share/plasma/desktoptheme/kubuntu/metadata.desktop
/usr/share/plasma/layout-templates/
/usr/share/plasma/layout-templates/org.kubuntu.desktop.defaultPanel/
/usr/share/plasma/layout-templates/org.kubuntu.desktop.defaultPanel/contents/
/usr/share/plasma/layout-templates/org.kubuntu.desktop.defaultPanel/contents/layout.js
/usr/share/plasma/layout-templates/org.kubuntu.desktop.defaultPanel/metadata.desktop
/usr/share/plasma/layout-templates/org.kubuntu.desktop.defaultPanel/metadata.json
/usr/share/plasma/look-and-feel/
/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