If you can't find a version from your current laptop manufacturer then I recommend 3RVX. This is the onscreen app I use for volume control myself. It offers the drag option under the speaker icon and it can be set for several onscreen volume indicators including some I made that offer bars across the bottom of the screen in blue, green or purple.
Note: 3RVX does NOT include an option for brightness so if you need that feature you will need to get software from the manufacturer.
3RVX is listed in our
Freeware Database under Mouse & Hotkey enhancements.