Mixed button sizes on one card

New-ish user and still learning my way around the interface. With the layouts below, the left is what I’ve got (with separate volume +/- buttons) but what I’d eventually like to do is one button/graphic with icons on either end (which would obviously still raise/lower the volume). Any way to accomplish this? Thanks!

Sorry for the light theme, there’s a bounding box around the two buttons on the right I swear