Sentinel 2A and 2B Harmonisation process implementation for raw data

As per this link Sentinel-2 processing baseline changes and harmonizeValues
Harmonisation process between Sentinel 2A and 2B has been implemented for data post Jan 2022.
Can anyone guide how this harmonisation process can be implemented on data obtained from AWS S3 bucket for all the years before 2021 as well as post 2022.
Thanks