The KD-50X80K NA is a 50 inch 4K TV from Sony. It was launched in 2022. It comes with a 10-bit VA panel. It can achieve a max resolution of 3840 x 2160 @ 60 Hz with a pixel density of 89 ppi.
Picture Quality
After screen size and resolution, the next most important spec of a display is its Color Reproduction Accuracy, which is defined by its color gamut specification.
This TV doesn't come with a color gamut specification, so we have to take a guess. Considering the TV features a big 50 inch screen, it won't come with a cheap panel, so here we can assume its equivalent sRGB coverage to be 90-100% or above. The color accuracy on this TV will be Lifelike! It will produce color accurate images AS IT IS intended.
Understanding the Color Gamut Specification
Color gamut spec of a TV is the measurement of the range of colors that the TV can produce.
A panel with poor color reproduction will produce washed out colors that will spoil your immersive experience.
It is specified in different units - sRGB,sRGB (standard RGB), NTSC 1953, DCI P3 Adobe RGB, rec.2020. It is upto the manufacturer which one they choose.
But don't worry, below is a chart that you can use to choose a TV with good color accuracy.
Now, after color gamut, the static contrast of a TV similarly impacts its picture quality.
Why its important?
A TV with low static contrast ratio will not produce deep enough blacks and possibly bleed backlight as shown below:

The above TV's static contrast is rated 800:1. So make sure you get a TV with a static contrast of >= 1000:1. Ofcourse, More the better.
Think of static contrast as another dimension to details — just like resolution. To put it into perspective, a TV with low contrast ratio will produce less shades of colors, so lesser detail overall.
If given a choice, always prefer a FHD TV with high contrast ratio over a 4K TV with low contrast ratio.
This TV comes with a static contrast ratio of 8000:1., well enough to achieve deep blacks. For the record, it also comes with local dimming technology which is a plus.
HDR is also supported on this TV in form of Dolby Vision, HDR10 and HLG (Hybrid Log Gamma).
Coming to brightness, it can go as bright as 250 nits. The backlight used on the panel is Direct LED.
Gaming Performance
If you aren't interested in gaming, you can safely ignore these specs. But if you are also going to use the TV for gaming or use it as a PC monitor, you would want to get a TV that features the lowest input lag and response time.
Unfortunately, Sony did not specify the input lag on this unit. Now, since this is not a cheap TV, we can expect an input lag of less than 20ms.
What is Input Lag and Why it matters ?
This lag is the latency at which your device inputs changes the content of the TV. Though, this won't matter much if you aren't into competitive/FPS games like call of duty.
For best of both worlds, look for a TV that features an input lag and response time of < 20ms.
Ergonomics and Dimensions
Coming to ergonomics — If you plan to wall mount the TV, you can make use of the VESA mount provided with this TV, which by the way has an interface size of 200 x 200 mm. The unit doesn't come with Swivel, Tilt or Pivot support.
Vertically, the TV measures 50 inches and horizontally 44 inches. It is 2.76 inches thick. It weighs approximately 12.4 kgs and 0.6 kgs extra if you include stand.
Hardware and Audio
The TV comes with a 1.8 Ghz Quad Core (ARM Cortex-A73) CPU while its graphics engine is handled by a (ARM Mali-G52) GPU. The available RAM on this TV is 4 GB.
For display connectivity, there are four HDMI 2.0 (CEC) ports and one AV Composite In 3.5 mm jack port on this TV.
For connecting USB devices, you will have two USB ports. Other connectivity ports include — 1x Cable/Antenna In (female), 1x RS232 (C) and 1x Ethernet RJ45.
Wireless connectivity options on this TV include a 5Ghz Wi-Fi, 2.5 Ghz Wi-Fi, Wifi-Direct, Bluetooth and DLNA.
The Audio unit of this TV is powered by 2 x 10W built-in speakers.
As for power consumption, on average, this TV consumes 50.4 Watts. On standby, it takes 0.5 Watts.
Both 110V and 220V outlets are supported on this unit.