How to process the native response in API gateway for response codes other than 2xx series?

Need clarification.
If in a particular API, I have 5 resources and since Conditional Error Processing isn’t resource/method scoped, and if i put this policy at the API level, so the only way to transform the native error format into a customized one is through invocation of a flow service in Conditional error processing.
Then for the 5 resources depending on their resource path, i can set the customized error structure. Is there any other solution besides this?