Hi Rakesh
One of the key benefits of using both Systems Manager and MR is the Sentry capability:
https://documentation.meraki.com/SM/Deployment_Guides/Systems_Manager_Sentry_Overview
This allows you to leverage certificates for authentication, that are delivered securely to devices (in fact, the private key for the cert stays on the device itself). Instead of you having to build and maintain both RADIUS and Certificate Authority infrastructure, Meraki Dashboard does this for you
If a device is removed from manage, we also remove the entry in RADIUS, resulting in the device not being able to authenticate against the network. And because the cert is bound to MDM, it means that if the device is unenrolled, then the certificate is removed also
The documentation should be self explanatory, but if you've any questions, let us know.