How are motion graphics like this created?
Totally doable using After Effects as it comes out of the box. 

I'd be making each letter a separate layer, turning that layer into a matte for the colour, which would be provided by the gradient ramp effect (there's a subtle red-purple gradient in the letters). The reveal would be done by either making an animated mask to control the moving colour, or the stroke effect with the brush size large enough to fill the strokes of the letters.

3D extrusion is done with the built-in 3D extrusion in the ray-traced 3d renderer. You'd have to pre-comp the coloured layer probably ifyou're using track mattes etc.

The movement would be a combination of keyframes and the wiggle expression.

There are probably a dozen more ways to do something like this–this is true for anything in AE.