Question

is ozymandias a metaphor

Answer 1

The statue of Ozymandias is a single metaphor for power and legacy, both political and otherwise. The desert sands whittles away at the statue, representing the destructive power of the sands of time on power and rule.

Answer 2

Yes, it is. The statue of Ozymandias metaphorically represents power, legacy, and command. It clarifies the meanings of the object and makes it clear that once the king was mighty and all-powerful.  It also shows that the sand has eroded the actual shape of the statue, representing the destructive power of time.