You can specify that Autonomous Database uses a private endpoint inside your Virtual Cloud Network (VCN) in your tenancy. You can configure a private endpoint during provisioning or cloning your Autonomous Database, or you can switch to using a private endpoint in an existing database that uses a public endpoint. This allows you to keep all traffic to and from your database off of the public internet.
Specifying the virtual cloud network configuration allows traffic only from the virtual cloud network you specify and blocks access to the database from all public IPs or VCNs. This allows you to define security rules, ingress/egress, at the Network Security Group (NSG) level and to control traffic to your Autonomous Database instance.