Creating a WhatsApp-like app is not that hard as you are thinking. You should follow these steps below if you are still confused that how to create an app like WhatsApp.
• Select a suitable business model for your app.
• Find a team of experienced developers.
• Structure your app.
• Add Minimum Viable Product (MVP) features.
• Build an amazing design for your app similar to WhatsApp.
Is there any other idea to own an app that works just like WhatsApp?