Yes, you can charge and/or discharge your Expansion Pack 3000 separately from your Power Bank.
You can use an AC charger cable, a car charger cable, or up to 400W of solar input to charge your Expansion Pack.
This battery has one XT60 output port, one USB-A output port, and one USB-C output port.
IMPORTANT: When your Expansion Pack is connected to your Power Bank with a cascade cable, do NOT use the input ports on both devices simultaneously. Only use the input ports on your Power Bank 2000.