With the AWS Identity and Access Management (IAM) policy simulator, administrators can now simulate permissions boundary policies along with other permissions policies to better understand the effective permissions for IAM principals (users and roles) in their AWS environment. Additionally, developers can now use the policy simulator to debug issues related to permissions boundary policies.

from Recent Announcements: https://aws.amazon.com/about-aws/whats-new/2020/01/aws-iam-policy-simulator-now-simulates-permissions-boundary-policies/