While inmate Cut-Throat is right about not needing a 128GB microSD card, perhaps you plan to store your music there as well ??
If Volumio allows to use the 'excess' space for music storage you'll be in great shape.
Another option might be to create a small partition for Volumio and a separate large partition for music storage.
And yet another option (and simplest) would be to get another smaller capacity microSD card for Volumio and use the 128GB microSD with a USB to microSD card adapter. You will then be able to plug the microSD card into a standard USB port on the Raspberry Pi and use it for music storage.
P.S. You do use Etcher to burn the Volumio image onto the microSD card. However, I don't know if Etcher allows you to burn to a separate partition on the microSD card. You might have to try creating the partitions ahead of time.
Good luck !
