Palm Color: Change the color of the character’s palm and under feet. To change the look, change Color Attributes Limbs, Red Color of the selected basemesh.
Basemesh ‣ Properties Editor ‣ Object Data Properties ‣ Color Attributes ‣ Limbs ‣ Red Color
Blend: The blend value is used to change the visibility of the Palm color. At 0 it’s not visible, at 10 it’s at full visibility. Default value at 5.