You can measure the dimension of a 55 inch TV (138cm) by calculating the diagonal length, from the upper left-hand corner to the lower right-hand corner.

Resolution is a term that describes the density at which these minuscule dots, known as pixels, are arranged on the display. These individual pixels come together to form the image that is visible on the screen. As a result, a greater pixel count directly correlates with a higher resolution, yielding a clearer and more detailed picture.
55 inch TVs are offered in both 4K and 8K resolutions. The 4K version features a resolution of 3840 x 2160 pixels, providing a high level of detail and clarity in the image. The 8K version provides even greater detail and clarity, with a resolution of 7680 x 4320 pixels, which is four times the number of pixels found in a 4K TV. With this ultra-high resolution, it becomes possible to display incredibly sharp and detailed images.

The optimal viewing distance when watching a 55 inch TV is 1.69 m (5.5 ft).
The most immersive viewing experience is achieved when 40 degrees of your field of view is taken up by the screen.