Note:
This idiom can also be expressed as "has its sights set on", "has her sights
set on", "have their sights set on", and so on.
Origin: Metaphorical, and related to the fact that a person using a gun looks
through the gun's sights in order to aim, and will have his sights set on the
target before shooting at it.
https://www.englishclub.com/ref/Idioms/