Can I buy Apple Watch with cellular Sim free?

The Apple Watch has an eSIM, which gets programmed to the carrier of your choice. It DOES NOT have a physical SIM card.

There are 2 Apple Watch cellular radios

• Canada, U.S. Mexico, Puerto Rico

• The rest of the world

Carriers will not attempt to connect to an Apple Watch that does not use the correct radio.

If you do not get your Apple Watch in your own country, you may have to return the Apple Watch to the country where purchased to get warranty service.

If you do not get your Apple Watch in your own country, there may be country specific restrictions in the installed Apple Watch software that prevent features from working when you get home.

watchOS - Feature Availability - Apple

Apple watch cellular is sim free only. It can be paired with your iphone and cellular service will be assigned.

Check this Apple Watch - Carriers - Apple (IN)