Hello shiv55,
Welcome to the Apple Support Communities, and it appears there are some issues with setting up cellular data on your Apple Watch. We'll do what we can to help.
Make sure to go through all the steps here (including any important updates) for setting up cellular data on the Apple Watch: Set up cellular on Apple Watch
If you're still having issues, continue partnering with your carrier for any other additional steps.
You can also reach out to Apple Support directly here: Get Support
Thanks and have a wonderful day.