From settings you can choose a wall paper to remove the neon background
As for the icons, I found some methods to do it but it seems tedious. Basically you will download the old icon and replace the new icon. It looks like a manual search process and you'll have to do this icon by icon.
Think of the haters in your life as sandpaper; they’ll scratch you up time and time again but in the end you’re polished, smooth, and spotless..while they end up useless
We make a living by what we get, but we make a life by what we give.