What are two options for expanding storage space on a Cisco router?

Two options for expanding storage space on a Cisco router include upgrading the existing flash memory or adding an external storage device. Upgrading the flash memory involves replacing the current memory module with one that has a larger capacity, while external storage can be achieved by using USB ports or SD card slots available on some Cisco routers to connect additional storage devices. Both methods enhance the router's ability to store configurations, logs, and other data.