For the 21:9 screen ratio in Destiny Ark, players usually feel more comfortable than the 16:9 resolution. However, if we forcefully stretch the screen ratio, black bars will appear on the top and bottom of the screen.
First of all, the appearance of black borders is due to the built-in setting of the game that forces the screen ratio to be stretched.
We need to open the NVIDIA Control Panel and add a 21:9 resolution in the custom option of "Change Resolution", such as 1890*810.
After that, restart your computer and re-enter Destiny Ark. You should be able to find the 21:9 aspect ratio option in the settings.
If you want the image to completely fill the screen, you can choose to buy a widescreen monitor or force fill the screen in the NVIDIA control panel.
After setting the 21:9 aspect ratio, you can use the free part of the screen to use other applications at the same time.