@Debbie Edwards Edwards Thank you for reaching out to Microsoft Q&A, apologize for any inconvenience caused on this.
Could you please help us with the documentation link that you are referring to create a logic app using PowerShell ?
I have come across this documentation, where it is clearly mentioned that before you create\update the logic app using Azure PowerShell you need to create a workflow definition(JSON formatted file) for your logic app.
Then you need to pass the path of the workflow definition file to
-DefinitionFilePath property for New-AzLogicApp cmdlet.
Feel free to reach back to me if you have any further questions on this.