Hello @Harish Kumar ,
Thanks for the question and using MS Q&A platform.
As an alternative you may try exploring ODBC connector in ADF (I haven't tested this but you can give a try). I have seen that one of the Postgre connector document says we can use ODBC connector to establish connection Postgre in GCP using ODBC connector with SSL.
Here is the ref document: ODBC Linked service properties
In case if that doesn't help, I would recommend submitting a feature request feedback in ADF IDEAS forum here: https://feedback.azure.com/d365community/forum/1219ec2d-6c26-ec11-b6e6-000d3a4f032c All the feedback shared in this forum are actively monitored and reviewed by respective product teams. Please do share the feedback link once it is posted so that we can share it with internal team.
Hope this info helps.
Thank you