It depends on two things: Screen resolution and how many metres there are between where you sit and where the TV will be. Use our TV distance calculator to get an accurate calculation.
If you buy a screen that is too big and sit too close to the TV, you may find that the picture is blurred or that it is difficult to see all the details. This can make the viewing experience worse, even if the TV is otherwise of high quality.
It is therefore important to choose a screen size that suits the distance between you and the TV so that you can have a comfortable viewing experience without discomfort or poor picture quality.