Are you talking about dielectric constant vs temperature. Yes in general it is true. With the application of electrical field there are several possibilities e.g. increase in domain size, swapping of ionic conductivity and so on. By the way you have not mentioned name of material and magnitude of peak etc. What is the effect on loss or loss factor?

Peak permittivity in the ferroelectric phase transition when an electric field is usually shifted to higher temperatures.

My experience in poled relaxor ferroelectric materials shows that peak in dielectric versus temperature curve indicates a structural transformations. In a ferroelectric material, increasing electric field strength eventually will give domain saturation hence constant dielectric and piezoelectric properties.