To charge an XPS with a powerbank, it must be able to do the following:

XPS must have USB-C with PD (as far as I know, all XPS with USB-C can do this).

Powerbank must be capable of USB-C with PD (Power Delivery) and deliver at least 20V 2.25A (in PD mode).
Unfortunately, PD alone is often not enough, as most devices require at least the 20V 2.25A (45W) profile...

Unfortunately, it does not work.

I ordered it and just tested it, unfortunately it does not charge my XPS 13 2-in-1. Very very disappointed!

should be possible

Yes, this should be possible with the appropriate cable.