Mosaicing large number of S2 images

I am working on a project which covers a study area demanding around 15 S2 tiles and 20 spectral indices from each image. For this, my problem is to mosaic all the images and indices for this huge study area. I wanted to download a single mosaiced image for the study area using earth engine but it doesn’t allow me to download everything at once. I am also finding problems with mosaicing two or more stacks of images in the correct order. Is there any easy way to perform this operation on any platform?
Thank you.

Depending on your project’s goals, you might consider NASA OCSSW level-3 bins (using the new l2bin64, etc. for small bins) rather than mosaics.

Thank you for your answer but I am not familiar with this thing. Could you please simplify?

NASA’s ocean colour workflow creates level-3 binned files from level-2, then combines
these to end up with global files for various time-periods. Currently, the workflow produces netcdf files that contain a processing history that you can follow back to the level-2 input files. The OCSSW software does have some support S2, but I don’t know if it can handle level-2 files from other processing systems, or whether binned data are suitable for your project.

GPT has a Binning operator, but it isn’t compatible with NASA’s OCSSW binning.

For the basic ideas behind binning: IOCCG Guide to Creating Level-3 Binned Products

For the OCSSW Software: