Microphone not working on IPhone 7 plus

Hey there ,

See>>>If the microphones on your iPhone aren't working - Apple Support

good luck!

Ok, then the support article link is what you should try next. If that doesn't help, then I suggest contacting Apple Support directly for further assistance with this issue. You can do so, simply by selecting the "Get Support" link in the upper right-hand side of this forum's web page.

Is this issue only when using WhatsApp or any app that requires the microphone?

Ref: If the microphones on your iPhone aren't working - Apple Support

Not only WhatsApp, the issue is for all the apps