So the angular momentum of light would be put under the same category as polarization, which is a property that a single photon can have?
Or is it a property like wavelength, momentum, frequency, intensity, etc -- a property of light that can be observed only when the light is a system of lots of photons, instead of just an individual photon?
Also, sorry if my categories are wrong. If so, I hope it doesn't take away from my main question of whether it is a property of a single photon or a property of a system of photons
Orbital angular momentum is also a property of single photons, related to the shape of their wave function. You can read about it and see some example shapes on the wikipedia page https://en.wikipedia.org/wiki/Orbital_angular_momentum_of_li...
I can't think of a property of light that is only in the bulk and not at the single photon level (somebody correct me if I am wrong). But I haven't read this paper in any detail to find if the "torque" is a bulk property or a single photon property.
Intensity is number of photons per unit area per unit time, so it takes many photons normally, but a single photon produces a non-zero intensity.
Objects also have other internal (non-space/position) related properties. For example, light has polarization. These properties can and do change with the passage of time. For example, you can change the polarization of light with a strong magnet. Relativity can and does place some restrictions on how this evolution happens, in so far as something is moving in space, but that is a more involved story.