As per the question it is given that,

The side of the cube $=9cm$

The largest cone that can be cut from cube will have the base diameter $=$ side of the cube

$2r=9$

$r=9/2cm=4.5cm$

Now,

Height of cone $=$ side of cube

Thus, height of cone (h) $=9cm$

Volume of the largest cone to fit in $=1/3\pi {{r}^{2}}h$

$=1/3\pi \times {{4.5}^{2}}\times 9$

$=190.93c{{m}^{3}}$

Therefore, the volume of the largest cone to fit in the cube has a volume of $=190.93c{{m}^{3}}$