Disk size shows the same after cloning a small disk to a larger disk

The remaining GB (difference between 120gb and 2TB) of your hard drive are free and must be manually assigned to a new partition or assigned to drive C (Resize the partition)

You can do it manually. In Windows, go to Computer Management and Extend disk space. If you do not want to do it manually you can use applications like AOMEI Partition Assistant Standard, GParted, etc.

HowTO resize partition or create a new partition with AOMEI