On the other hand, if you want to replace the app icon with your own image -- or you don't have iOS 18 -- you'll have to use the Shortcuts app. How to customize an app's icon using the Shortcuts app ...

Once you do that, you’ll have a clean-looking themed icon ready to be used, all while looking fantastic on your screen. Advertisement - scroll for more content.

A big part of the iOS 18 update is the new home screen experience. You can finally place apps and widgets wherever you want on the screen, have dark mode icons, and even use tinted app icons.

Because of this quirk, I find it's best to do the search from a page that doesn't have that icon on the page, or maybe even a blank screen. Now you can create as many icons for an app as you want!