Hi @Prashantha Damle ,
Thanks for reaching out to Microsoft Q&A.
If the device has already been joined in Microsoft Entra ID/Azure AD, the official supported method for Intune auto-enrollment is to use a provisioning package- https://techcommunity.microsoft.com/blog/intunecustomersuccess/bulk-join-a-windows-device-to-azure-ad-and-microsoft-endpoint-manager-using-a-pr/2381400
You can also use script, here is the non Microsoft link- https://call4cloud.nl/enroll-existing-entra-azure-intune/
Please do not forget to "Accept the answer” and “up-vote” wherever the information provided helps you, this can be beneficial to other community members.