Yes we can find lost smartphones using imei number.
If you are having iphone mobiles you can find your phone by signing in to icloud account and using its "Find my phone" feature.
if you are having android phones you can find your phone by signing in to samsung account and then download ADM app and use its "Find my device" feature.
For more details refer to this link below:
https://www.quora.com/How-can-I-track-a-phone-through-its-IMEI-number
