A possible solution to moderation is allowing communities to delete a parent comment (+ the child comments) from that community w/o actually fully deleting the comment
Therefore if you view that specific post with the context of a specific community, you only see the comments that are not deleted, which have (most likely) been moderated already
If you view the source post directly, you would see all the comments for that post
Lemmy instances can enable an option to prevent non-admins from creating communities, so if it isn’t available on your instance (usually in the header area on the website) then your instance admins have disabled that option