"Tell that its sculptor well those passions read
Which yet survive, stamped on these lifeless things
The hand that mocked them, and the heart that fed;"
The poem presents negative views about the power used to impose will
It also comments on the arrogance and pride that can come from thetype of tyrannical power in which the ruler wishes only be to known for his percieved greatness.
Ozymandias sees glory in a statue that is critical, yet his confidence in his own supremacy means he overlooks any evidence that contradicts their grandeur.
"Mocked" can also be interpreted as "to make a model of" as the sculptor has literally made a model of the king - perhaps it was not his intention to portray him negatively - he had a "heart that fed" the king through its intention to please him - but that simply by modelling Ozymandias - it was inevitable that his cruelty would show due to it being an inextricable part of him.