What is the largest known pyramid by volume in the world?

The Great Pyramid of Cholula.

This pyramid can be found in Cholula, Puebla in Mexico.

It is constructed with adobe brick. While not as high as the Great Pyramid of Giza, it is much wider, and formerly served as a temple to the god Quetzalcoatl.

Dimensions of the Great Pyramid of Cholula:
25 m (82') high with a base 300 m x 315 m (984' x 1,033')

Dimensions of the Great Pyramid of Giza:
146.6 m (481') high with a base 230.3 m x 230.3 m (756' x 756')

https://en.wikipedia.org/wiki/Great_Pyramid_of_Cholula