Find a full reference of all btp CLI commands and their parameters here: btp CLI Command Reference.
You can create, update, and move Neo subaccounts to directories using the btp CLI, but if you want to actually access a subaccount in the Neo environment, you need to work with the Neo command console or the SAP BTP cockpit. See Working with Neo subaccounts using the SAP BTP command line interface for the known conditions and scope when working with Neo subaccounts in the btp CLI.