"feature of existence" is correct and usable in written English.
You could use it to refer to something that exists as a characteristic, observable or significant element. For example, "Adaptability is a defining feature of existence for many species."
In the space of half a lifetime we have gone from taking those features of existence as a given, and proceeded through the crudest IVF processes, to the point where the design of life-forms is possible.
Rand's conception of the role of metaphysics is fairly minimalist; its task is the investigation of the most general features of existence as such of "being qua being," in Aristotle's phrase.
The aim was to compare the various hospital departments in according to the features of existence of L. pneumophila in the environment of hospitals.
The fact that we are beings with bodies is no accidental feature of our existence in the world.
As discussed, conflict exists as a corollary of P. juliflora invasion and as a feature of Afar existence.
This fact, one that I had never even considered before I returned to the land of a thousand welcomes, now became the defining feature of my existence.
An outstanding feature of his existence was his ability to attract the goodwill of patrons prepared to relieve him of the responsibility of providing for his livelihood.
In one prevalent view, the very meaning of salvation is emancipation (moksha) from this morass, an escape from the impermanence that is an inherent feature of mundane existence.
"Some of my students regard it as the defining feature of their existence, the thing that gives their life meaning when everything else seems out of their control," he said.
Heidegger believed that Western philosophy was hopelessly preoccupied with unworldly abstractions like those of logic -- Descartes, for instance, had singled out disembodied thought as the defining feature of our existence.
