@Newbie_ss Did you ever solve this? I assume your issue is that an Oracle client was not deployed/installed within the environment where your DAG was being executed. From what I understand cx_Oracle still relies on an Oracle client to be present on the host to establish a connection to the Oracle database.
I have successfully gotten this to work using a pre-built Docker image from Oracle, my local Windows environment, and a semi-hacky way within the astro CLI Debian build (see Connecting to Oracle database from the Astronomer Airflow image).
I ended up having to install the Oracle instant client RPM files myself within the image, set up a tnsnames.ora and the TNS_ADMIN environment variable, and then it would connect.
I think that the preferred way to do this would be to build a custom Dockerfile that does all of this for me and then use that as the base for my Astronomer Airflow.