Yes, according to the theory of special relativity, the space between the objects will appear to shrink for an observer in relative motion with the objects. This effect is known as relativistic length contraction or Lorentz contraction.
Relativistic length contraction occurs when objects are moving relative to an observer at a significant fraction of the speed of light. According to special relativity, as an object moves faster, its length in the direction of motion appears to contract from the perspective of an observer at rest relative to the object. This contraction is proportional to the object's velocity and is given by the Lorentz factor:
L' = L * sqrt(1 - v^2/c^2)
Where: L' is the contracted length as observed by the observer, L is the proper length of the object (measured when the object is at rest), v is the velocity of the object relative to the observer, and c is the speed of light.
In the scenario you described, where two objects are moving at the same constant speed, one behind the other, an observer in relative motion with the objects will perceive the distance between them to be contracted due to the relativistic length contraction effect. This contraction occurs along the direction of motion.
It's important to note that the observed contraction is relative to the observer's frame of reference. From the perspective of an observer at rest relative to the objects, there would be no length contraction. Relativistic effects, including length contraction, become more significant as the relative velocity between the observer and the objects approaches the speed of light.