Hello @RJ and welcome to Microsoft Q&A.
It sounds like you are saying you need to make 2 calls, one to fetch some metadata for use in making the second call.
In this case, you can use a Lookup activity for the first call, and use a portion of the output in the second. The second would be a Copy activity with REST as source and Data Lake Parquet as sink.
Please tell me if I misunderstood.