Is it Possible to Modify the DisplayName Attribute when Provisioning Users for an Application?

We are setting up automatic provisioning for the Zendesk service desk application in Entra. The Name attribute for Zendesk users is mapped from the DisplayName attribute in Entra

Our user's display names are currently set up using the Lastname, Firstname format. But we would like to modify the DisplayName attribute when an account is provisioned so that the Name on the Zendesk account uses the Firstname Lastname format.

I've been testing a wide variety of expressions (I can post some of them if it helps). But I just keep getting one invalid expression error or another.

Does anyone know if this is possible?