I am learning the Coulomb's law. So I have question, If $q_2$ be 4 times more than $q_1$, would the force from $q_1$ to $q_2$, still be equal to the force that pushes from $q_2$ to $q_1$?
As an aside: The force F on an electric charge $q$ in an electric field E is F = $ q $ E.
For two charges $q_1, q_2$ separated by a distance $r$ you can think of it in two ways:
(1) The first charge creates an electric field E$_1$ = $ q_1 /4 \pi \epsilon_0 r^2$ at the second charge and the force experienced by this charge is $ q_2 E_1$.
(2) The second charge creates an electric field E$_2$ = $ q_2 / 4 \pi \epsilon_0 r^2$ at the first charge and the force experienced by this charge is $ q_1 E_2$.
(forgetting about vectors for the moment)
In both cases the result is $$ q_1 q_2 / 4 \pi \epsilon_0 r^2 $$
When you take into account the direction of the electric fields you see that the forces are equal in magnitude but in opposite directions.