Windows 10 and 11 do not have a native "underscan" slider in the standard Display Settings menu. However, you can sometimes mitigate the issue by ensuring your resolution is set correctly.
When you connect a PC to such a screen, the computer sends the full image, but the display zooms in and cuts off the edges—effectively cropping your taskbar and Start menu. windows overscan
If your TV lacks a 1:1 pixel mode: