You can attach the specified managed policy to the specified user. You use this API to attach a managed policy to a user. To embed an inline policy in a user, use PutUserPolicy. The following attach-user-policy command attaches the AWS managed policy named AdministratorAccess to the IAM user named Alice.
$ aws iam attach-user-policy --policy-arn arn:aws:iam:ACCOUNT-ID:aws:policy/AdministratorAccess --user-name Alice