AWS CloudFormation | How can I reuse resources that were already provisioned?

Hello,

With the AWS CloudFormation IaC generator (infrastructure as code generator), you can generate a template using AWS resources provisioned in your account that are not already managed by CloudFormation. Use the template to import resources into CloudFormation or replicate resources in a new account or Region.

https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/generate-IaC.html#generate-template-console

and once you create a template from IaC generator you can start import existing resources into Cloudformation by creating a CF a stack. Here is the documentation, https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/resource-import.html

Resources that supports import can seen here: https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/resource-import-supported-resources.html