You generally cannot track a phone that is fully switched off in real time
Check the last known location in Google Find My Device or Apple Find My
Review location history in your Google or Apple account if it was enabled
Contact your mobile carrier to ask about the last network connection
Report the phone as lost or stolen to the police
Provide the device IMEI number to the carrier and police
Use any linked smartwatch, tablet, or account to help locate recent activity
Enable Lost Mode or mark the device as lost in your account
Monitor for the phone coming back online and send a ring or lock command
Change passwords for important accounts if the phone may be compromised
If the phone is powered off and has no battery, wait for it to reconnect to a network or Wi-Fi