Is it mandatory to specify –style argument and –tag-transform-script in osm2pgsql query for importing .pbf file?

I am trying to build a tile server that serves tiles of multiple styles(osm and osm-bright). I have followed this link for implementing this. But here I found that osm2pgsql query for importing .pdf file is specifing the --style argument and --tag-transform-script for importing data to postgres database.

osm2pgsql -s -C 300 -c -G --hstore --style openstreetmap-carto.style --tag-transform-script openstreetmap-carto.lua -d gis -H $HOSTNAME -U postgres [.osm or .pbf file]

So my question is that - Is it mandatory to use --style argument and --tag-transform-script osm2pgsql? If yes , what should be the alternate way for serving multiple styles?