packages/SystemUI/res/drawable/media_output_icon_volume.xml

<vector xmlns:android="http://schemas.android.com/apk/res/android"
    android:width="24dp"
    android:height="24dp"
    android:viewportWidth="24"
    android:viewportHeight="24"
    android:tint="?attr/colorControlNormal"
    android:autoMirrored="true">
  <path
      android:fillColor="@color/media_dialog_item_main_content"
      android:pathData="M14,20.725V18.675Q16.25,18.025 17.625,16.175Q19,14.325 19,11.975Q19,9.625 17.625,7.775Q16.25,5.925 14,5.275V3.225Q17.1,3.925 19.05,6.362Q21,8.8 21,11.975Q21,15.15 19.05,17.587Q17.1,20.025 14,20.725ZM3,15V9H7L12,4V20L7,15ZM14,16V7.95Q15.125,8.475 15.812,9.575Q16.5,10.675 16.5,12Q16.5,13.325 15.812,14.4Q15.125,15.475 14,16ZM10,8.85 L7.85,11H5V13H7.85L10,15.15ZM7.5,12Z"/>
</vector>