Which AWS service provides this functionally?

Explanations:

AWS Service Catalog is used to create and manage catalogs of IT services that are approved for use on AWS, but it does not automate account creation or prevent EC2 instance creation.

AWS Organizations allows for the management of multiple AWS accounts and can enforce policies through Service Control Policies (SCPs) to restrict actions such as EC2 instance creation.

EC2 Image Builder is used to automate the creation of EC2 images, but it does not facilitate account creation or prevent EC2 instance creation across accounts.

AWS Systems Manager is primarily focused on managing and automating tasks across AWS resources, but it does not handle account creation or policy enforcement for instance creation.