The poem uses a blend of Petrachan (14 lines) and Shakespearean (irregular rhyme scheme) sonnet, traditionally a way of writing love poems.
The sonnet form allows Shelly to simultaneously mock Ozymandias' lack of love and respect, but to ridicule his excessive hubris that resulted in this infatuation and love with barbaric power.
The poem uses iambic pentameter.
This is used as a motif of control. It is used throughout the poem in order to demonstrate the frightful regularity of the oppression by those in power on those they rule.
They are constrained by the oppressivetyrant that rules them.