1.
Enter the game and press f 1 1 in the game to change the game from window mode to full screen mode.
2.
If you can't press f 1 1, it may be that your display screen is widescreen, so you need to click the right mouse button on the desktop, select the nvidia control panel, select the item on the left to adjust the size and position of the desktop, select the second item on the right without zooming in, and then enter the full screen of the game.
3.
Whether it can be full-screen is related to your graphics card program. Some are forced to be proportional, so both sides of the game are black and cannot be full-screen. Some are stretched by default, so that it can be full screen.