Can I Reduce the Size of a VPC CIDR Block?

Based on AWS documentation, it's not possible to just change the CIDR block of your current VPC. You need to create a new CIDR block and manage your subnets from there. Here's a source that outlines the necessary requirements: [AWS Docs](https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/aws-resource-ec2-vpc.html#cfn-ec2-vpc-cidrblock).

You can only create and delete VPCs with a single main CIDR. Direct downsizing isn't an option.

You can't directly shrink an existing VPC CIDR. The only way to do it is to create a new VPC in the desired size, set up the necessary routes and resources there, and then migrate over everything from the old VPC before deleting it.

Unfortunately, no. The easiest approach is to add a smaller CIDR block for the new VPC and migrate resources. What are you trying to accomplish by resizing?