You can select auto scaling during provisioning or later using the Scale Up/Down button on the Oracle Cloud Infrastructure console.
When you select auto scaling Autonomous Transaction Processing can use up to three times more CPU and IO resources than specified by the number of OCPUs currently shown in the Scale Up/Down dialog. When auto scaling is enabled, if your workload requires additional CPU and IO resources the database automatically uses the resources without any manual intervention required.
To see the average number of OCPUs used during an hour you can use the "Number of OCPUs allocated" graph on the Overview page on the Autonomous Transaction Processing service console. See Console Overview for more information.
Enabling auto scaling does not change the concurrency and parallelism settings for the predefined services. See Managing Priorities on Autonomous Transaction Processing for more information.
See Add CPU or Storage Resources or Enable Auto Scaling for the steps to enable auto scaling.