How to track iPhone with out ‘find my’ app?

You don't need a Find My app; you can use any internet browser and go to www.icloud.com/find

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

If you mean that Find My was not turned on in Settings before the phone was lost or stolen, see the information in If Find My iPhone or Find My iPad isn't enabled on your missing device - Apple Support including the following:

If your missing device doesn't appear in the Find My app or at iCloud.com/find, you didn't turn on Find My. There's no other Apple service that can find, track, or flag your device for you. But there are steps that you can take to help protect your data.