polygerrit-ui/app/elements/change/gr-change-metadata/test/plugin.html

<dom-module id="my-plugin">
  <script>
    Gerrit.install(plugin => {
      plugin.registerStyleModule('change-metadata', 'my-plugin-style');
    });
  </script>
</dom-module>

<dom-module id="my-plugin-style">
  <template>
    <style>
      html {
        --change-metadata-assignee: {
          display: none;
        }
        --change-metadata-label-status: {
          display: none;
        }
        --change-metadata-strategy: {
          display: none;
        }
        --change-metadata-topic: {
          display: none;
        }
      }
    </style>
  </template>
</dom-module>