New MacBook Pro 16" Overheating without any load

What do you mean by overheating? A Mac notebook is a lot of processing power in a small, thin package and processing generates heat. Expect your Mac to get very warm/hot just above the keyboard/tough bar (that's where the CPU/GPU are) and on the bottom (Apple calls these notebooks not laptops for a reason). The Mac will regulate it's temperatures with fans, and it will throttle back the CPU/GPU if needed, so as long as you are keeping your Mac notebook within acceptable operating temperatures, it will perform properly. The keyboard and palm rests should remain comfortable to touch, and if they don't then contact Apple for service.

The fans spin at a base speed of 1,500 to 2,000 rpm and at those speeds you won't hear them. Under higher loads the temperatures go up and the fans can run up to 6,000 rpm – you'll hear them when they speed up. Incidentally, streaming video uses a fair amount of processing power, particularly if you are using Chrome as your browser.

FWIW, the CPU/GPU of my 16" MBP are normally at around 40 °C, and those chips sit right under the area above the Touch Bar (the case there isn't that hot, but the chips under it are and a lot of that heat goes up through the aluminum case). Under heavy processing loads the processors can go to 70-80 °C or higher (even up to 100 °C, although above that the Mac will throttle back the processors to reduce the temp).

Apple doesn't publish 'normal' internal temperatures. But 70-80 °C is a perfectly normal operating temperature for a CPU or GPU. The bottom line is that your Mac will protect itself, increasing fan speed when the chips reach higher temperatures, throttling back the processors if the fans can't keep them cool enough, and if need be shutting itself off. So, as long as you are using it in a room temp of 50-95 °F, it can maintain it's internal temps appropriately.

The area above the Touch Bar is going to get pretty warm, that's normal.