The rate of acceleration is not dependent entirely upon voltage to the motor. You must go back to your lower school education to recall and understand Newton's First Law. Look up "inertia" if you don't recall the lesson.
If you require a jack-rabbit start, you might want to consider that in real life, that doesn't happen. Most modelers pay extra to get more prototypical starts and stops. Adding voltage will just get the wheels spinning, without necessarily getting the train moving, or will shred the traction tires, if your trains are equipped with them. See "inertia" again and also "co-efficient of adhesion." It would take lots of trial and error to effect a balance between loco mass, wheel adhesion, voltage, curvature of the track ahead, weight of trailing cars, etc.
A motor start capacitor, in industrial applications, is placed in the circuit, then, when the motor has achieved approximately 75% of its top speed, the capacitor is removed from the circuit, generally using a centrifugal contact. I would suspect that trying to do that inside a toy train would be mechanically problematic, unless you are really clever, or really small.
You might need to lengthen the blocks to allow the following train to have room to slow down. Or shorten the trains themselves.
If the following train is always the same length, and it always stops in roughly the same spot, you COULD wire the controlled block where the locomotive sits with a slightly higher track voltage, getting it going with a kick, then have the next section of track wired with a slightly lower voltage. It would require a transformer such as a ZW or a couple of phased transformers for the two adjacent track sections.
