How to traffic data between Google Cloud SQL and Flutter?

Cloud SQL documentation about connecting with external apps didn't helped me much. Isn't there some library to handle data traffic like Firebase's Cloud Firestore and Realtime Database offer?

How do I connect Google Cloud database to SQL?

In the Google Cloud console, go to the Cloud SQL Instances page. To open the Overview page of an instance, click the instance name. Select Connections from the SQL navigation menu. In the Authorized networks section, click Add network and enter the IP address of the machine where the client is installed.

Does Google Cloud support SQL Server?

SQL Server running on Google Cloud works with all of your familiar tools like SSMS and Visual Studio. Connect your existing workloads to the best of what Google Cloud has to offer.

Either use cloud functions to provide an API for Flutter and access to the DB
or run your custom server in the Google cloud that does that.

SQL databases should never be accessed over the internet directly and instead hidden behind a web server that only exposes a limited or specialized API.