Inherent optical property (aph)

As part of a project, I used sentinel-3 OLCI Level 2 (WFR) images. I would like to know if it is possible and what is the process from these data to bring out the inherent optical property (aph) of chlorophyll in order to establish a link with the concentration of chl-a

As far as I know there is no way to derive the IOPs from the L2 water product.

If you are using the CHL_NN data, you can use the C2RCC processor. This processor uses the same neural net for processing andin addition provides you with the IOPs.
For the CHL_OC4ME data, there is no way to get to the IOPs.