How do whales sell off hundreds of millions worth of coins at once?

Is there some secret exchange that has low fees for insane volume ? I know they sell it off slowly but isn’t the fees going to be absurd regardless ? Coinbase has their no fee subscription but it seems dumb to use a kyc exchange to mass sell off. Can someone enlighten me what that understands more of how whales in all markets end up doing it ? Any and all info would be very appreciated. I’ve been in crypto since 2019 but I’ve yet to truly understand how whales accomplish most of their trading / market manipulation