Dark mode and light mode switch
A prototype made in Figma:
https://www.figma.com/proto/lYobaXsjKWgsbVvIoE4xDg/Select-Theme?node-id=113%3A584&viewport=928%2C314%2C0.5141118168830872&scaling=min-zoom
And you can watch the process in this video:
https://www.youtube.com/watch?v=PxTcMxxsKng&t=73s