If your PC houses an Nvidia GPU you can launch Nvidia Control Panel and create TS20xx-specific Profile and enable V-sync there. I didn't go that route. Instead, I used TS2021's own in-game settings configurator to switch the game from Full Screen to Borderless Window. That did the trick for me. I've no earthly idea why, but it worked. Also, I should point out that my 'tearing' was largely of items close to my camera position, such as locomotive cab interiors and telegraph/telephone poles at trackside, and was noticeable mostly while 'panning'. So maybe not what you are experiencing?
