[This is meant to be a practical rather an academic answer, intended for fellow students]
As the above comment helpfully says, the usage you found is not particularly unusual or literary.
I can't comment on how extreme the use of 姿 gets in a literary context but if, like me, you are trying to grasp the breadth of its normal use over and above its familiar use as "figure" or "appearance" then I think the easiest way is know a few key sentences (or at least this is what I am doing). I made a point of remembering and then focus on grasping the following few:
本来の姿 | proper state / real character
母の姿が目に浮かぶ | my late mother comes to mind (note context)
〜姿を見せる|appear on the scene
And, as it was an important word to understand, being alert for new/variations on these.
I put the following list together using some more of my own examples and the Apple dictionary (which seems close to Daijisen in content)
1 外見,身なり/appearance:
男の子はみすぼらしい姿をしていた|The boy was shabbily dressed.
___________________に姿をやつす|disguise oneself as_______
2 体の格好/figure
母の姿が目に浮かぶ | my late mother comes to mind (note context)
トムは後ろ姿がジムにそっくりだ|When seen from behind, Tom looks exactly like Jim.
3 人の目に映る体,その人/"sightings of a person"
あれっきり彼は姿を見せない|We have seen nothing of him since. /That was the last we saw of him.
彼は姿を隠した[くらました]|He went into hiding.
4 物の形/shape of an object
間もなく湖が姿を現した|Soon the lake showed itself [came in view].
太陽が何日も姿を見せなかった|The sun remained [stayed] hidden for days.
5 ありさま,様子/condition, circumstances
本来の姿 | proper state / real character
それが民主国家の本当の姿だ|That is what a democratic country should be like.