is wifi calling available in iphone se?

The iPhone SE does support Wi-Fi calling. However, you must be using a cellular carrier that supports it.

Wireless carrier support and features for iPhone in the United States and Canada - Apple Support

See my response above. That’s why.

There is no wi-fi calling on SE under Settings -> Phone. Os is up to date.

it's at the phone settings. if don't see it, search Wi-Fi through settings. I have the SE too