How to transfer games from one external HDD to another?

I’m replacing a 4TB external HDD with an 8TB external drive. I know that the 4 only supports one external HDD and I can just redownload everything but I have a strict monthly data cap (1TB per month) plus it is much faster and more efficient to transfer data between drives (that other console can easily transfer between drives because it supports more than one external).

So is there a way to transfer in lieu of redownload?

The only way I found was moving from the external to the system's HDD, unplugging the source HDD, plugging the new HDD and moving from them from the system into the new one.