Hi Vinoth, Greetings of the day!
Please check this doc for complete step by step process for retrieving certificate from KV
https://learn.microsoft.com/en-us/azure/key-vault/certificates/quick-create-portal
And here you can find the steps to use that certificate for packaging
https://learn.microsoft.com/en-us/dotnet/maui/windows/deployment/publish-cli?view=net-maui-8.0
Kindly check , accept the answer , if it helps , Thanks!