To change your crosshair, open the Menu and select “Options.” From here, choose “Controls” then “General,” before clicking “Reticle.”

Here is where you can begin customizing how your crosshair looks.

Under the “Type” drop-down menu, you can select Default, Circle, Crosshairs, Circle and Crosshairs, or Dot. While this may be enough for many, if you’re looking for more customization options, you’ll want to select the advanced options.

Source: https://www.distractify.com/p/how-to-change-crosshair-overwatch-2