Why is the LittlestTokyo.glb model so small?

There is the animation/keyframes example on the website. The model is called LittlestTokyo.glb — It is very light — just 4 MB — How it was compressed or prepared for export?

This is explained here:

It’s a combination of DRACO compression and texture optimization (e.g. using textures with lower resolution or JPG instead of PNG).