Lets just analyze a point charge to simplify this
Firstly we need to understand how is electrical energy is transferred, so you're gonna have to stay with me for a second.
Electrical energy is transferred through photon--waves, so it is quantized. We can imagine one of these quanta to be the crest of a three--dimensional wave. Think of bubble expanding in size over time centered on our point charge (field lines are basically just the direction of propagation of this wave. This is our electrical energy, the amount of energy contained in this bubble is constant. This energy (E*) is a function of charge (Q) and the "vacuum permittivity constant "e":
$$ E* = Q\cdot e_0$$
This Electrical energy is distributed equally along the wavefront (the surface of the bubble), therefore the energy at a point(E) is dependent on the total energy (E*) and the surface area of the bubble (A =4*pi*r^2):
$$E = Qe_0/(4\pi e^2)$$
The constants in this equation are condensed into one constant K, and it is neatly rewritten as Coulomb's familiar law.
$$ E = KQ/r^2.$$
Now That we (hopefully) understand this law let's discuss electric field lines.
Electric field lines are basically just arrows pointing in the direction of wave propagation, as drawn above. They are used to represent the direction of the energy (and subsequent force on a charged particle) that is emanating (in the form of photon wave bubbles) from the point charge. These lines are describing where a wave is going, thickness in these lines, then, would be describing how much it is going there you could describe the magnitude of the electric field and a point with thickness of the lines at that point if you so desired, but this is not standard. When multiple charges are involved, their "energy waves" can interfere constructively and destructively, producing field lines that are no longer radial and slightly more difficult for me to draw. electric field lines are only a visualization technique, not a physical reality in nature. The amount of field lines is really only dependent on how detailed a human "artist" wanted to get with their visualization of an electric field. My drawing has 8 field lines; this, however, means only that I was a being lazy but it can tell you nothing about the system which I have described. If we were to try to visualize all POSSIBLE field lines in a system, we would end up trying to trace the velocities of all photons present in a wave front; this is not possible, and even if it were, I would advise against trying it.