Parameter file generation

GROMACS version:
GROMACS modification: Yes/No
Is it possible to create a topology parameter files for a bigger molecules like LPS using CgenFF platform ? - " getting an error saying : readmol2 warning: atom or bond number too high; skipped molecule "

You should not attempt to generate topologies for huge molecules; this goes against force field transferability. Use small model compounds and piece the larger topology together. You will probably find that you should not even be using a general force field because everything you need for such a species is already in the parent force field.