There are two ways to backup your WhatsApp chats from your iPhone to Google Drive: manually or automatically.
To backup WhatsApp chats manually:
=> Open WhatsApp and go to Settings > Chats > Chat Backup.
=> Tap Back Up Now to start the backup process. Depending on how much data you have, it might take a while for the backup to finish. Once it’s done, you’ll see a confirmation message saying, “Backup complete.”
Auto backups happen daily and will save your new messages since your last manual backup. To turn on auto backups:
=> Open WhatsApp and go to Settings > Chats > Chat Backup.
=> Tap Auto Backup and select a frequency: never, only when I tap Back up, or daily.
To use a third-party app like iMazing, first download and install the app on your computer. Then, connect your iPhone to your computer and launch iMazing. Select “WhatsApp” from the list of options, then choose “Backup.” Choose a location for your backup file, then click “Save.” Your chat history will be backed up to your computer.