Thanks much for the clarification.
I have another question related to lat-lon and line-pix. I have lat-lon of in-situ data points and I am using lonlat2linpix function to get corresponding line and pixel in the image to extract them. I am doing this for OLCI, OLI, and MSI using their respective spatial resolutions. I am not re-projecting L2 image. Is that a problem?
Also, is there a way to figure out from L1 image if it is cloudy?
Thanks. a lot for your help.