From what I can understand, the Principled BSDF incorporates a ton of 'PBR-friendly' parameters into one compact box of sorts. For instance, I can attenuate a material's roughness, transmittivity and what not
One thing I am not able to zero in on is as to how Fresnel is incorporated into Principled BSDF. I'd figured at first that the IOR parameter, might have a hand in doing so, since we find it on the Fresnel node as well
However, it yields no difference:
Clearly, the IOR parameter does not seem to affect how 'Fresnel-y' the material is in Principled BSDF for a lack of better words. So how exactly does Principled BSDF handle Fresnel? How would I go about changing whatever values control the Fresnel, just as I would with a Fresnel node?