Hi @Mukilan M,
In Graph api you could use following api to get Tenent Setting
GET https://graph.microsoft.com/v1.0/admin/sharepoint/settings
Here is the document for reference
https://learn.microsoft.com/en-us/graph/api/sharepointsettings-get?view=graph-rest-1.0&tabs=http
To connect SPOOnline with ModernAuth, you could use following cmdlet
Connect-SPOService -Credential $creds -Url https://tenant-admin.sharepoint.com -ModernAuth $true -AuthenticationUrl https://login.microsoftonline.com/organizations
Here is the document for reference
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