The new Galaxy Watch 6 & Watch 6 Classic both support calling feature. You can make a call & answer it from a Galaxy Watch 6. If you have an LTE variant, then you don’t need your smartphone to make a call or receive it. If you are using Wi-Fi only variant, then you should stay connected with the paired smartphone. You can use in-built mic & speaker to make conversation.
For the LTE model, you have to activate calling plan from your telecom operator. For Wi-Fi only, it uses paired smartphone to dial a number & answer it. Both variants store you contacts, call history and other details.