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
There are shortcuts to happiness, and dancing is one of them-Vicky Baum