How much new ADU build increase value of the home in california

[Suganya Vinayakam]

I'm currently constructing an ADU in Southern California. While I haven't remodeled the main house, it's situated in a highly desirable neighborhood. I'm interested in understanding the increase in value that the newly built ADU will bring to the current value of the property. will it be appraised for same cost per-sqt as like main house? Did anyone appraise the property / sold after adding adu?