Is there anyway to merge an internal and external SSD such that both storage volumes become one?

I have a MacBook Pro 13" (2019), however purchased the 128GB storage option which is far too small. To compensate, I purchased a WD passport 256GB SSD. I have it plugged into my MacBook 24/7, so I was wondering instead of having two separate volumes of storage, could I perhaps merge them into one large storage volume, such that it showcases that I have ~384GB of storage in the storage option on 'About this Mac'? It would be a lot easier to have one volume of storage to store everything I need, rather then have to continuously choose the location. Many thanks.