Hi Santosh
the RAM-to-Disk ratio for SAP HANA systems is fixed and defined during the system setup.
There is no build-in command to grow or add data volumes.
If your instance should "grow" and your server allows for more RAM and CPU usage then you can take a backup of the existing system and restore it into a new system that had been set up with the larger data volume.
Alternatively, since scale-up is not all that often an option, you might use scale-out instead and add not just more disk, but also new nodes.
But the one-persistence-per-node is a core concept of the shared-nothing cluster of SAP HANA.