What follows applies to Bluetooth sound devices generally with Windows 10. Most often, when you pair and connect a Bluetooth device, Windows then recognizes both its own internal sound card as well as the Bluetooth device, with sound being directed as it had been initially (which is usually to the computer's speakers or a plugged in wired headset).
If you use Windows Key+B to throw focus to the System Tray, then arrow over to your volume settings, when more than one sound device is active there will be a choice of sound devices, and switching from the built-in Speaker/Headphone option to whatever your Bluetooth device is shifts audio output to that device in many instances (there are times this doesn't work, but it's what I'd try first). Once the Bluetooth device is selected, the volume slider applies to it. A word of warning if you are using earbuds or a headset, and have no idea what the computer volume setting is for that Bluetooth device, it's better to keep them somewhere other than right in/on top of your ears when doing the initial switch over. I have been absolutely blasted on a couple of occasions because my laptop speakers are crap, and need to be turned way up, while the Bluetooth devices are not, and an equal volume used with them is deafeningly loud.
Brian - Windows 10 Pro, 64-Bit, Version 20H2, Build 19042
[Regarding the Supreme Court refusing to hear the case brought by Texas to overturn the votes certified by 4 states:] Pleased with the SCOTUS ruling, but also immediately slightly terrified of where this crazy train goes next. We should know by now there’s a bottomless supply of crazy.
~ Brendan Buck, former adviser to Speakers of the House Paul Ryan and John Boehner