In AWS, generally a VPC is created with one CIDR block followed by creating multiple subnets that are subsets of VPC CIDR block.
However, what would be the use case to create 2 or more CIDR blocks for a single VPC? Is it to allocate more space in the same VPC when subnets within one CIDR block has reached its host limit Or are there any specific design considerations where this approach is followed?
Is it to allocate more space in the same VPC when one CIDR block has reached it host limit
Yes, that is the primary use case. From the announcement of this feature:
This feature has two key benefits. First, customers, who are launching more and more resources in their VPCs, can now scale up their VPCs on-demand. Second, customers no longer have to over-allocate private IPv4 space to their VPCs - they can allocate only what is required at the time, and later expand it as needed. With these benefits, this feature can make it significantly easier for customers to manage their private IPv4 address space.
