How can i find my wife’s lost iPhone now

I'm guessing your wife has a different Apple ID than you. Go to Find My, Tap on ME, the scroll down on the menu, you should find Help a Friend. That opens iCloud.com to help someone locate their phone.

If she is part of your family sharing group, see the following from Locate a lost or stolen device - Apple Support

1. Open the Find My app.
2. Choose the Devices tab.
3. Select the device to see its location on the map. If you belong to a Family Sharing group, you can see the devices in your group.

If not, then see the following from the same link:

You can help a friend find their device if it's missing and has Find My [device] turned on:

1. Open the Find My app.
2. Choose the Me tab.
3. Select Help a Friend.
4. Have your friend sign in to iCloud with the Apple ID they're signed in with on their missing device.

If you're using Family Sharing just open the Mind My app and select devices and all devices under the family sharing account will show up. Otherwise, log onto www.icloud.com with her ID and password to find her device.

If she's not a member of your family sharing group (or you haven't set up family sharing). Log into iCloud.com/find using her iCloud account from a browser.

You're welcome.