To set a different ringtone for each WhatsApp contact, you will first need to download the ringtones you want to use. You can do this using a whatsapp. Once you have your ringtones, you can follow these steps to set them:
Open GBWhatsApp on your mobile device.
Go to the chat with the contact you want to set a custom ringtone for.
Tap on the contact's name at the top of the chat screen.
Tap on "Custom notifications"
Under "Ringtone," select the ringtone you want to use for that contact.
Repeat the steps for each contact you want to set a custom ringtone for.
Please note that the process may be different on some devices, but should be similar.