Which Apple watches can make calls without phone nearby

In addition,

• you have to have an iPhone 6s, SE, 7 or newer.
• You have to have an iPhone carrier that supports the Apple Watch because the Apple Watch shares the iPhone's phone number, and the carrier will charge you a monthly fee for this service. In the U.S. the fee is $10 per month added to the iPhone cellular bill.
• Cellular Apple Watches are regional. So it is best if you buy the Apple Watch in the country where you are going to be using it.

iPhone Cellular Carriers that support the Apple Watch, which models, the radio frequencies each model uses, and the country where they offer service:

https://www.apple.com/watch/cellular

Just the GPS plus cellular versions;

Apple watch 3,4 and 5