Why does ozymandias refer to himself as kings of kings?

Ozymandias refers to himself as the king of kings in order to glorify himself. he thinks that there is no one who can equal him in any respect. the fact that he refers to himself as the king of kings shows his obsession with vanity and glory.

I met a traveller from an antique land

Who said: "Two vast trunkless legs of stone

Stand in the desert

Near them, on the sand,

Half sunk, a shattered visage lies, whose frown,

And wrinkled lip, a sneer of cold command,

Tell that its sculptor well those passions read

Which yet survive stamped upon these lifeless things,

The hand that mocked them, and the heart that fed:

And on the pedestal these Words appear:

"My name is Ozymandias [Ramses], king of kings:

Look upon my works ye mighty and despair!"

Nothing beside remains, Round the decay

Of that colossal wreck, boundless and bare

The lone and level sands stretch far away

Percy Bysshe Shelley (1792-1822)