I have an iPhone. Since iPhone can sign a message from bech32 address how do I do that.
What Bitcoin wallet is installed on your iPhone device?
If you want to try signing messages on an iPhone, use the Bluewallet wallet. It's easy to do and the method is not much different from using an Android device.
Because I'm not a Bluewallet user on an iPhone, I'll show you how to sign messages via an Android device.
Press the [...] button in the top corner of the application, then click the
Sign/Verify Message button. The address will be automatically filled in and the next thing to do is press the
Sign button, then the Signature will be filled in.
The method above is done on Android.