Yes, Samsung Galaxy Tab S6 LTE does offer voice calling.
The device also supports a slot for 4G sim slot.However, the device lacks NFC ( Near Field Communication)
In the meantime , you can check all the detailed specifications and latest updates on this device here.
No, the Samsung Galaxy Tab S6 LTE does not have the headphone jack and it only has the USB Type-C port for everything.
Check its look-
Check Full Device Specifications Samsung Galaxy Tab S6 LTE