GSC? does that stand for gamesense free? if so then yes
you can get sorryproxy, launch gs on 2023 and select your 2018 exe once the game loads (addon will make you select it when u open)
then join 2018 servers
but most of servers have plugins to prevent proxy
and when you do join a server, be ready to miss all shots since animations and resolver logic have completely changed from 2018 to 2023