Many AWS services support KMS and this allows you to encrypt your data using the CMKs that you create in KMS or with AWS-managed keys.
The list of AWS services that support KMS is very long. However, some important services from a developer perspective include EBS, RDS, SNS, SES, CodeBuild, CodeCommit, CodeDeploy, CodePipeline, S3, Glacier, Lambda, Redshift, Kinesis, DynamoDB, SQS, and CloudTrail.
You can find the complete list of services supported by KMS at https://docs.aws.amazon.com/kms/latest/developerguide/service-integration.html.