Inspiron 5593 Type C Port inquiry

@Silent-Nudge The Setup and Specifications document for that system, available on support.dell.com, specifically says that the USB-C port does not support Power Delivery, which means it can't be charged that way.  It also says it doesn't support display output, so it does indeed appear to be a data only port.

However, even if USB-C charging was supported, most power banks do not have the wattage output capacity to charge laptops.  You only said you have an Anker 20000 power bank.  That isn't very helpful because Anker makes a lot of 20000 power banks, but the "20000" is its energy storage capacity, which is measured in mAh (or sometimes WHr).  You need to look at its energy output capacity/delivery rate, which is measured in W (watts).  Most power banks only provide 10-18W output in order to support smartphones and tablets.  The Setup and Specifications document for your system indicates that it uses either a 45W or 65W power source, possibly depending on the specific hardware you have, such as whether you have a discrete GPU.  Check the power adapter that actually came with your laptop to see its wattage output.  There are some power banks that support 65W output, like the Dell PW7018LC.  It offers 65W output and 65WHr capacity, which is roughly equivalent to 20,000 mAh given 3.3V output of Li-Ion cells.  But as you'll see, the PW7018LC is quite a bit more expensive than a more typical power bank that has a similar storage capacity but a significantly lower output capacity.