There is a slider that effects the philtral. Middle Upper Lip Width.
This slider sorta effects that area too. Overlip Curve Slider.
To just effect the philtral and not the lip, you’ll need to ask someone who can use milkshape (3d program) and target that area of the face. This would be someone who has made geom based sliders.
I am unable to use the correct 3d program on my computer. Thus, I’m a bond-based slider maker. This means I don’t use a 3d program to find the bonddelta.
Sorry that I can’t help.