Indeed, if you're tired of the look of that dusty ol Mail app or if you just want to add a personal touch to your phone, you can change the look of any app icon. There are two ways to change them.

Big thanks to Redditor Straight_Random_2211 for sharing their custom dark icon assets and process, which we've distilled below: On your iPhone, download the "Get App Icon" shortcut: [Shortcut Link].