WhatsApp messaging app owned by Meta, has introduced a new feature that allows users to lock individual chats with either a password or biometric authentication. This feature aims to provide users with enhanced privacy and security for their conversations. If you're interested in using this feature, 
here's a step-by-step guide on how to do it:

Update or Download the Latest Version of WhatsApp: Make sure that you have the most recent version of WhatsApp installed on your Android or iOS device. You can find the app in the respective app stores and update it if necessary.

Choose the Chat to Lock: Open WhatsApp and navigate to the specific chat that you want to lock. This could be an individual conversation or a group chat.

Access Chat Settings: Tap on the contact's name or profile picture within the chat to access more options and settings.

Select "Chat Lock": Scroll down the options and locate the "Chat Lock" feature. It should be positioned below the disappearing message settings. Tap on it to proceed.

Enable Chat Lock and Authenticate: You'll be prompted to enable the chat lock feature. Follow the instructions on the screen to set up your preferred method of authentication, either a password or biometric authentication such as fingerprint or face recognition, depending on the capabilities of your device.

Once you've completed these steps, the selected chat will be locked and require authentication to access it. Now, let's look at how you can view locked chats on WhatsApp:

Open WhatsApp: Launch the WhatsApp app on your device, and you'll land on the home page displaying all your chats.

Access Locked Chats Section: Swipe down on the screen to access the locked chats section. Here, you'll find a list of all the chats that you have locked on WhatsApp.

Select a Locked Chat: Tap on the locked chat that you want to access from the list.

Authenticate to Unlock the Chat: To unlock the chat and view its contents, you'll need to provide the required authentication. This could involve entering your password or using biometric authentication methods like fingerprint or face recognition.

By following these steps, you can effectively lock individual chats on WhatsApp and enjoy enhanced privacy and security for your conversations.

Please note that the specific instructions and available features may vary depending on the version of WhatsApp you are using. It's always a good idea to consult the official WhatsApp documentation or check for updates within the app to ensure you have the most accurate and up-to-date information.