To explain my question in a better way I will first talk about gravitation!
Gravity is not a force and the effects of gravity are ascribed to spacetime curvature
Gravity was explained in a better way by Einstein than by newton i.e If I ask newton what causes gravity and how can two objects placed far apart attract each other, he wouldn't be able to answer properly.But, Einstein can and he would give a lecture on General theory of relativity.
The major drawback of newton's theory of gravity is that it considers gravity to be a instantaneous force.Relativity puts a limit to the speed with which information can travel.
I think that electrostatic force can't be instantaneous, because there is a limit to the speed with which information can travel.
How do you explain electrostatic force?
Let's talk about electrostatic force between two opposite charges and gravitational force between two other objects.The electrostatic force follows the inverse square law similar to newtons law of gravity.But,we know that Newton's concept of force doesn't accurately describe gravity.Gravity is a consequence of curvature of spacetime.So,if I ask a question: what is the cause of gravitational force and why it isn't instantaneous, you could explain me General relativity.
But,what if I asked you: what is the cause of electrostatic force and why it isn't instantaneous ?...
To put it simply:
I just want to know if there is a prevailing theory which explains electrostatic force more fundamentally than the inverse square law and also the fact that electrostatic force isn't instantaneous