You can do this in two ways:
From Facebook Business Manager, in the settings of your WhatsApp account.
Or directly on Wax, in the account settings.
From Facebook Business Manager
Go to your Business Manager, in the WhatsApp section via this link.
Follow the steps below:
From Wax
Log in to your Wax account via this link.
Recommended dimensions:
Ideal size: 500 x 500 pixels
Format: Square image (ratio 1:1)
File size: Keep the file under 5 MB for fast loading
Supported formats: JPEG or PNG
Tips:
Avoid blurry images: use a high-resolution picture for maximum clarity.
Centering: place the main subject in the middle, since WhatsApp crops the image into a circle.
Minimalism: choose a simple image with a clean background so your brand or picture stands out clearly.