If your meter can measure AC millivolts, use a shunt. You’ll have to build a special cable from an extension cord. Cut either the live or neutral wire, insert a shunt, which is a resistor with a very low resistance (typically milliohms), then provide some taps at either end of the shunt. Make it all electrically safe. You don’t want to do the 50/60 Hz Shuffle.

Plug in the extension cord, plug your TV into the extension cord, then measure the AC voltage across the shunt while the TV is operating and apply I=E/R. Now you know the current in the circuit. Measure the wall outlet voltage and use P=IE to determine the power. The measurement is accurate when the power factor of the device being tested is close to 1.

But honestly, plug-in consumer-level power meters like the Kill-A-Watt are MUCH safer to use, relatively inexpensive, and work for appliances with power factors that are not 1 (like motors). They read out voltage, wattage, and energy usage (KWh).