It's not confirmed when the Meta AI shortcut will be available to WhatsApp users. The AI chatbot isn't available everywhere so it might take some time before reaching all users. In addition to creating AI-powered images, Meta AI can be used to answer queries, fetch videos or simply have a conversation.
To access Meta AI on WhatsApp at present you can type @MetaAI in a chat window and type in your queries. You will be directed to Bing AI for answers to your queries.
The new WhatsApp layout with the Meta AI search bar is yet to reach users in India. It looks like the update is rolling out in a phased manner but soon all WhatsApp users should have easier access to Meta AI. The new feature also shows Meta's plans to deeply integrate AI in all its products and services.