How do I track an iPhone?

Use any internet browser and log into www.icloud.com/find

Also see the following Apple articles for information about lost or stolen iPhones or iPads: If your iPhone or iPad is lost or stolen - Apple Support and

Find your lost Apple device or AirTag with Find My - Apple Support

Hopefully, the Find My option was enabled on the phone....and....the battery has not run down.....and....the phone has not been powered off......and.....the phone has an Internet connection where it is located.

That's a lot of "if's".

If all of these things are true, you can locate the phone online by entering www.icloud.com/find in any browser and then enter the Apple ID and Password associated with the phone.

More info here: If your iPhone or iPad is lost or stolen - Apple Support