Hi @Dhamley ,
In your case, you can grant unique permission to moderators on site pages and document libraries.
Assuming the moderators have at least Edit(Site members) permission level in your case. Go to the library you don't want those users to view or edit, click "Library settings" in the gear and click "More Library settings". Select "Permissions for this document library". Click "Stop Inheriting Permissions" from the ribbon. Select all groups and click "Remove User Permissions" in the ribbon.
Then grant unique permissions to the users based on your need.
See this for more details: https://support.microsoft.com/en-us/office/customize-permissions-for-a-sharepoint-list-or-library-02d770f3-59eb-4910-a608-5f84cc297782.
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