I'm trying to find out which version of the Sen2Cor processor was used by the ESA to process a Sentinel L2A product for a specific date. The latest version is Sen2Cor v2.8 which was published this year. However, for data of the last two years the ESA had to use a different version. I can't find any information about the used Sen2Cor in the metadata when I am download L2A products via the Copernicus Open Access Hub. This information would be necessary to decide whether to process a Sentinel L1C product with the new Sen2Cor processor or not.
You can check the processing baseline in the MTD_MSIL2A.xml file (inside .SAFE) under the tag . Sen2Cor v 02.08 started with the processing baseline 02.12. But notice that the S2 PDGS is using more versions than the public sen2cor versions. For example, this is some of the sen2cor versions used in some processing baselines: