Did you already take the step of formatting the drive using the V20?
I have successfully done this using:
2TB portable HDD - https://www.amazon.co.uk/Seagate-Portable-External-Creative-Photography/dp/B00G7LQA1E/ (gets its power though USB, hence the Anker-powered USB-C hub)
With USB-C hub ( Huawei MateDock but should also work with e.g. similarly operating ATZEBE )
Power Delivery (PD) power source (in my case this Anker https://www.amazon.co.uk/gp/product/B072K5SFHG ) - to power the USB-hub (using USB-C to USB-C cable) which in turn powers the HDD and charges the V20.
The only caveats are:
You will need to format the HDD using the V20 (exFAT). NTFS formatting did not work for me.
It is not a very dynamic setup. It is easy to forget to properly eject the HDD when you want to pick your V20 and go out and about.
5TB might be too big, though. MicroSD is limited to 2TB, perhaps USB-attached HDDs / SSDs too?
Also check my comment in u/c0mplexx 's year-old post: