Ozymandias was a king who loved himself more than his subjects. He was a self-absorbed megalomaniac with the notion of being the mightiest ruler in the whole world. Insensitive and haughty in temperament, he was self-obsessed and arrogant.
Consider the following lines describing the face of Ozymandias's ruined statue:
Half sunk a shattered visage lies, whose frown,
And wrinkled lip, and sneer of cold command,...
"Frown" is an expression of disapproval and displeasure, while "sneer" suggests contempt and disrespect for others. Being "cold" is being unaffectionate or lacking warmth of feeling or sensitivity. These expressions substantially illuminate the character traits of Ozymandias. They suggest that he was hardly concerned with the happiness and sorrow of his subjects. He derided them, and used them as his puppets.
Moreover, Ozymandias would commission his giant statues to be erected across his empire. On the pedestal of one such colossal statue, he got engraved the following lines:
My name is Ozymandias, King of Kings;
Look on my Works, ye Mighty, and despair!
This further reveals the ruler’s personality traits. First, instead of using the royal treasury for the welfare of his people, Ozymandias would drain it away in erecting his mammoth statues. The egomaniac king derived pleasure in such futile and extravagant activities, which were carried out with the revenue collected from his citizens.
Second, it demonstrates Ozymandias’ self-love and vanity. He’s boastful of his works and takes pride in calling himself the “King of Kings.” He asks the other rulers to cringe at his great works and give up the hope of ever matching him in strength or accomplishments.