It facilitates expansionist attitudes about as much as the Dalish culture facilitates genocide. Possible in theory, advocated by some extremists, absent in practiced policy. It's about as inherent as, oh, the American political motif of spreading freedom and democracy across the world equating world conquest.
Even the point about the total conversion of 'heretical' peoples is overstating it. The Chantry doesn't maintain a policy of mandating conversion and expanding the Chant by conquest of nonbelievers for the purpose of conversion itself- as the Dev's have mentioned before, they've broadly taken the stance that the True Religion will ultimately come on top on its own, without needing to be forced at sword point. The only mass forced-conversion in the history of the setting directed by the Chantry itself was in the creation of the Alienages, and even that comes with the caveat of it being uncleare if the elves were allowed to refuse and join the Dalish exodus. One could argue that the Exalted Marches against Tevinter were an attempt, but it would be ignoring that the religious schism corresponded with the return of the Tevinter mageocracy and its abuses of magic and slavery- as much a political struggle as a religious one.
I’ll have to reply to this in parts.
The Chantry doesn't need to maintain a policy to root out heretics. No group has impacted life in Thedas more than they have. The Chantry is the dominant religious organization in the known world, and its influence prevails across most of the kingdoms therein. There is propaganda inherent within their theology that hinders diversity, and propagates racism, xenophobia, and the marginalization of people who do not share the same beliefs as them, and elves in particular. Even humans who do not believe in the Maker pay it lip service, for fear of persecution (and Leliana was ostracized for having a different interpretation of the Chant, despite her fervent belief in the Maker). Religious monopoly can do more harm than any military force.
The Chantry teaches that non-humans are further from the Maker. Because being at the Maker’s side is associated with virtuousness (and the opposite with sinfulness), this only reinforces the mistreatment of elves.
And as I mentioned before, it was on the authority of a Divine that the alienages were instituted, which segregates the elves, encouraging their isolation and substandard status. That same Divine ordered that that all Chantry art depicting elves be destroyed, with only a single statue of Shartan being spared, albeit with his ears docked, which seems to be the Thedosian equivalent of lightening skin tones. Furthermore, Shartan’s writings have been suppressed, and any verses in the Chant that mention him have been removed.
The power the Chantry holds over the general population’s education becomes evident when you consider that Shartan’s existence, or at least his participation and aid in Andraste’s rebellion, is not common knowledge. Most people in Thedas cannot read. Their illiteracy makes it easier to feed them misinformation, and to use that misinformation to influence their views.
Outside of the nobility, literacy is highest in the Chantry and its (former) affiliations- the Circle of Magi, the Templars and the Seekers. Even nobles are given a religious education alongside their academic one- the Human Noble warden and King Cailan, for example. The pen is mightier than the sword. Everyone from royals to poor commoners is indoctrinated by the Chantry through its education system, and the elves (and mages) suffer for it.
“Submit and become second-class citizens” or “be forced into the fringes of society” is not what I would call a choice, or at least, not a fair one, not when you’re forced between two unsavory choices (three if you count death). That is, if they were actually given it- officially. It’s still being forced. I’d say it’s more an illusion of choice than anything.
The idea that the Exalted Marches against the Imperium were as much a political struggle as a religious one is exactly the problem. The Chantry’s powerful political stake when paired with its religious monopoly is what makes them so dangerous for the elves, mages, and anyone who does not share their beliefs.
I understand where you’re coming from, but this is my take on it.