Hhmmm, do you mean a motherboard supporting 9th gen processors (i.e. with 300 Series chipset) or do you mean a motherboard with 9 Series chipset? Actually, it doesn't matter...
- A motherboard intended to support 9th gen processors DOES NOT support 6th gen processors.
- A motherboard with 9 Series chipset supports 4th and 5th gen processors; it DOES NOT support 6th gen processors.
Bottom line, the answer is no, regardless of which of the two questions you were asking.