"King of kings" - could be a Biblical allusion, but also shows Ozymandias' pride and ignorance
"shattered visage" - his "visage" is a metaphor for his legacy, which is broken
Desert setting - the sand correlates to the material of the statue and the erosion of it conveys how over time Ozymandias will become unimportant, like the millions of particles of sand
Ozymandias - the Greek name of Ramesses II
Structure - sonnet form is typically used for love poetry, suggesting Ozymandias' love for himself, but rhyme scheme is irregular reflecting Ozymandias' broken power