Salesforce Rest API create account

We are using the Salesforce Rest API to integrate our external website with Salesforce Sales Cloud. When a user registers on our website, we create a contact record in Salesforce. The response to the initial insert request includes the Contact ID. Is there a way we can have the initial request return more fields? On the SF side, we have a formula field that generates the 18 digits long contact ID and we need that returned to us for interacting with the Marketing Cloud. We can make another call to get this long contact ID but we are trying to avoid this extra call. Is what we are trying to do achievable?