With iOS 18.2, Apple added a variety of new choices within the Default Apps part of Settings, doubtless in response to antitrust scrutiny across the globe. Amongst them are the power to designate default calling and messaging apps, that are already supported by some third-party apps.
Now WhatsApp, which is arguably the preferred world messaging platform, helps these options.
Assist for default calling and messaging on iOS is listed as a characteristic for the WhatsApp testflight beta, however it seems to work simply tremendous with the most recent model of the iOS app within the App Retailer (model 25.8.74).
To make WhatsApp your default app for calling or messaging, open Settings, scroll down and choose Apps, then Default Apps. You’ll see WhatsApp as an possibility within the Messaging and Calling menus.