aws sts assume-root
Returns a set of short term credentials you can use to perform privileged tasks on a member account in your organization. AWS CLI reference
4 options Its page in the AWS CLI reference
Options
--duration-secondsThe duration, in seconds, of the privileged session.--minimum-session-token-sizeThe minimum size, in bytes, of the session token that STS issues for the request.--target-principalThe member account principal ARN or account ID.--task-policy-arnThe identity based policy that scopes the session to the privileged tasks that can be performed.