Whatsapp on Android lets you export a chat with or without media (images etc), but it limits the number of messages. With media you get the last 10k messgaes, and without you get the last 40k. Emojis are preserved though.
The limits are supposedly due to email size limits but, as they also apply when exporting to non-email endpoints like Google Drive, I suspect they're more to do with preventing people from moving their chats to other services.
Since some months (years?) ago, WhatsApp lets you set up your own encryption password for the DB backup. I set one up and used https://github.com/ElDavoo/wa-crypt-tools to get access to the decrypted SQLite and run some analytics over my messages :)
As for extracting from the backup DB, they'll be encrypted..