Determining the total drag of a propeller driven aircraft while turning with a load factor of n = 2?
Induced drag $D_i$ is proportional to the square of lift $L$:
$$D_i = \frac{2\cdot L^2}{\rho\cdot v^2\cdot\pi\cdot b^2\cdot\epsilon}$$
where $b$ is wingspan, $v$ is flight speed and $\rho$ is air density. $\epsilon$ is an efficiency factor which tends to be between 0.8 and 1. Compared to straight and level flight, induced drag will quadruple when turning at 2g and the same flight speed.
In order to know how much total drag goes up you need to know how much of your total drag is due to induced drag. Only then can the question be answered.
If your straight and level polar point is that for best range (when zero-lift and induced drag are equal), 2g flight at the same speed will increase total drag by a factor of 2.5.