How can I find my wife’s phone? Using my phone she lost it today?

If you use Family Sharing open the Find My app and tap on her name or tap on devices, then her phone. If you don’t see either tap on “me”, scroll down and tap “Help a friend”, then log in with her Apple ID.

A web browser can be used as shown at the beginning of step 1 here.

If your iPhone, iPad, or iPod touch is lost or stolen - Apple Support