TLDR: The form of this poem is a "Pindaric ode" (sometimes called an "irregular ode" and occasionally called a "Cowleyan ode") like Wordsworth's Ode: Intimations of Immortality from Recollections of Early Childhood. Since Pindaric odes are a form of poetry that never was common, and is currently dying out, today it is much more likely to be classified as free verse. The hallmarks of a "Pindaric ode" are a generally iambic meter, lines of varying length, and no fixed rhyme scheme.
This poem is in a loose iambic meter, and can be divided into lines which have sporadic rhymes. For example, consider the following excerpt:
The world in which the carousel will twirl
is not the hollow hell you fear; it is the world.
Just the world.
A world where if you’d wished to have a name
it must be stolen, carved and pulled
full-bloody from the frame
of others who would wish in vain
to hold their selfness close.
You want a face? Take it.
There are so many here,
and those who cannot hold them, well, whoever chose
to give them such a gift must take the blame,
knowing they could never keep it
in a world of so much thieving strangeness.
This in fact seems to be general form of Pindaric odes in English: they are iambic, have varying line lengths, and have no consistent rhyme scheme.
Odes are generally just poems in praise of something, but "Horatian odes" and "Pindaric odes" specify a certain formal structure for the poem. For Pindarics, this poetic form was introduced to English in 1656 by Abraham Cowley, who used this form to translate several of Pindar's odes, as well as to write some of his own poems, and who called them "Pindaric odes." Subsequent English poets modeled their Pindaric odes after Cowley's poems. So for example, when Wordworth wrote his Ode: Intimations of Immortality, it was generally called a Pindaric ode.
Since the English "Pindaric odes" bear relatively little resemblance to the odes written by Pindar in ancient Greek, a better name for them would be "Cowleyan odes" — and occasionally they are called by this name. They are also sometimes called "irregular odes", but this term is ambiguous, since it is sometimes applied to almost any poem that is labeled an ode.
Some websites specify more formal structure for Pindaric odes; for example, Poets.org says
Pindaric odes ... contain a formal opening, or strophe, of complex metrical structure, followed by an antistrophe, which mirrors the opening, and an epode, the final closing section of a different length and composed with a different metrical structure.
What that means is that stanzas come in groups of three—two with identical structure followed by a third with a different structure.
However, I believe this description of the structure of Pindaric odes mainly only applies to those written in ancient Greek. There were a few strict Pindaric odes written in the 16th and 17th centuries (for example, Thomas Gray's Progress of Poesy), but most English poems called "Pindaric odes" are actually irregular odes.
I cannot discern any regular changes in metrical structure in the various stanzas of Wordsworth's ode Intimations of Immortality. Nor can I discern any regular changes in metrical structure in the Abraham Cowley's ode The Resurrection, which begins
Not Winds to Voyagers at Sea,
Nor Showers to Earth more necessary be,
(Heav'ens vital seed cast on the womb of Earth
To give the fruitful Year a Birth)
Then Verse to Virtue, which can do
The Midwifes Office, and the Nurses too;
It feeds it strongly, and it cloathes it gay,
And when it dyes, with comely pride
Embalms it, and erects a Pyramide
That never will decay
Till Heaven it self shall melt away,
And nought behind it stay.
and ends:
Stop, stop, my Muse, allay thy vigorous heat,
Kindled at a Hint so Great.
Hold thy Pindarique Pegasus closely in,
Which does to rage begin,
And this steep Hill would gallop up with violent course,
'Tis an unruly, and a hard-Mouth'd Horse,
Fierce, and unbroken yet,
Impatient of the Spur or Bit.
Now praunces stately, and anon flies o're the place,
Disdains the servile Law of any settled pace,
Conscious and proud of his own natural force.
'Twill no unskilful Touch endure,
But flings Writer and Reader too that sits not sure.
Thus, these are not Pindaric odes of the original form used by Pindar, but Pindaric odes of the more irregular Cowleyan form.
