Modern LED TVs are usually tens of watts, not hundreds. A bright 65-inch set might be 80–150 watts while the picture is on. Four hours of evening TV is a small piece of a bill that also has heat and cooling. The habit that surprises people is leaving it on as hallway noise all day.
OLED and very large sets, or sets with a bright HDR mode, sit higher. Soundbars are a separate small card if you want them. Streaming boxes and game consoles add their own watts even when the screen is off — those are other items in Whatt.
Standby is usually a few watts. Eight hours of picture-on still dominates standby for anyone who actually watches.
Set screen-on hours and a typical wattage. Fine-tune if you have the Energy Guide or a meter.
At 18.8¢ per kWh, 100 watts for 5 hours is 0.5 kWh — about 0.09. All-day (12 hours) is about 0.23. Not nothing over a month, not an AC.
The stack
Soundbar, streaming stick, and console are other cards. Price the TV’s picture-on hours here, not the whole entertainment shelf unless you mean that.
Related
Usage estimate only — not a utility bill, load calc, or advice.