How can I set specular to 0 for all newly created texture materials?

I am currently importing 3D characters from the game World of Warcraft into unreal engine for an animation.

The issue is that when I import these characters they look extra shiny:

In the screenshot above, I have set the characters face specular value to 0 which looks how I intend it to look (and how I want it to look). World of Warcraft has flat lighting shading so adding PBR values to the textures make them look like they jumped in a tub of wax.

I was wondering if there was some sort of plugin that can allow me to set default roughness/specular values on material creation (from a texture) when I import these characters.

Bonus points if I can also globally set the roughness/specular values for all assets I import (which id imagine i could achieve via material parameter collections however id still need a way to automatically generate the parameter on all newly created materials.

PS. Each Wow Model generally has like 4-6 materials on each character, and i intend on importing 100 characters so i do not want to manually set each material’s roughness/specular.

Also please let me know if there is a better category for this question - Couldnt find a better fit