No, GrapheneOS has its own alternative implementation where users can completely revoke network permission from the app, it has been proven more robust a few times now, eg. https://review.lineageos.org/q/topic:%2213-firewall-bypassab...

My DivestOS features both the GrapheneOS and LineageOS implementation, and I document the former as block and the latter as "data restriction" (eg. to simply block over cellular) as it cannot guarantee a real block.