Technology
When you receive media file, the app automatically saves it to your gallery. The Media Visibility option is turned on by default. It affects new media and doesn’t apply to old.
Open WhatsApp and tap on any chat that you want to disable auto-download for. Now, go to the profile section of that chat by tapping on the name of chat.
Scroll down and tap again on Media Visibility. Tap on "No" to disable auto download on WhatsApp.
You must manually download any photographs, videos, or documents from that specific conversation after you stop this function since you turned off auto-download.
The other advantage of this feature is also that it will also save some amount of your mobile data.