One of my favorites is macOSicons.com, which lists over 25,000 alternative icons, meaning you should be able to find multiple options for popular apps with ease. macOS allows you to change an app's ...

The First Descendant confused many Destiny 2 players when they signed onto the game and noticed a number of icons that looked similar, if not nearly identical, to many found in Destiny itself.

You can set a dark or any icon of your choice – but the images have to me in the .ico format. Read: How to change File and Folder Icons. As an example, let us change the icon to a dark one.