The larger sized objects appear as the viewer hits the arrow keys or uses the trackpad. With the right arrow, objects become greater and greater in size, while the left arrow will reduce the objects back to the beginning screen.
So excited to share something I've been working on!
Introducing The Size of Space – an interactive visualization of the scale of the universe ?
— Neal Agarwal (@nealagarwal) October 27, 2019
via Flowing Data