Actually, IoT Central already contains both an IoT Hub and a Device Provisioning service.
Together with several other services, IoT Central provides a pretty complete SaaS IoT Portal for registering and monitoring devices. Next to that you can turn insights from the dashboards into actions using rules.
So, just start registering and connecting devices in IoT Central, you do not have to bring other services. If you want to integrate with other Azure resources, check out the export functionality.
IoT Central has the GA (Generally available) status. So you can run production loads on it.
Please check out this IoT Central learning path.
please take some time to follow the MS Learn modules to learn about all the good things IoT Central offers.
The short answer is that Azure IoT Rest APIs are available to provision devices in an automated way.