Change app icons without launcher or other app, is that possible?

I don't like the icons of the apps and I wanted to ask if you can change them without a launcher or another app and if so how. I have a Huawei so Android phone.

With the newer Android versions you can change the shape of the icons, but the icons remain otherwise the same in style and colors. Since you have to search in the phone settings, probably means something different on every phone. Otherwise I would not know that this is possible without third-party launcher. But what's wrong with installing one? Then you have free choice in the icons and usually many other setting options.