unity - How can I change the color of an object at runtime?

I wish to have the shader effect as in the game 'The stack' by ketchapp

https://play.google.com/store/apps/details?id=com.ketchapp.stack&hl=en

As you can see, the color of the objects as well as the skybox keep changing.

I'm completely c# noob and trying my best to find shaders to replicate the effect. But I can't find anything.

How can I change the color of an object at runtime?