How to authenticate PowerShell cmdlets in Runbooks with managed identities?

You can authenticate PowerShell cmdlets without AzureRunAs connections in Runbooks by using managed identities in Azure Automation. You can create a PowerShell runbook in Azure Automation that uses a managed identity, rather than the Run As account to interact with resources. You can assign permissions to the managed identities to allow them to stop and start a virtual machine. You can also create credential assets and use them in a runbook or DSC configuration. The cmdlets in the following table create and manage Automation credentials with PowerShell: Get-AzAutomationCredential, New-AzAutomationCredential, Remove-AzAutomationCredential, and Set-AzAutomationCredential. The Get-AutomationPSCredential cmdlet gets a PSCredential object that you can use with a cmdlet that requires a credential.

Have a look here
https://github.com/MicrosoftDocs/azure-docs/blob/main/articles/automation/learn/powershell-runbook-managed-identity.md
https://github.com/MicrosoftDocs/azure-docs/blob/main/articles/automation/shared-resources/credentials.md

Let me know how it goes !!