Can someone hack an iPhone physically?

In principle, a very good hacker can do such a thing but Apple is reputable in making sure that its devices are practically protected from hacking. Apple's devices are not perfect. They are not really hacking-free but the measures applied by Apple and your compliance to the protection of your device will prevent any hacking successful.

They cannot. Nothing is 100% impossible but given that a few years ago even the FBI couldn't get into an iPhone after days and days of trying I think it extremely unlikely your finder managed to do so.

About Face ID advanced technology - Apple Support

"The probability that a random person in the population could look at your iPhone X and unlock it using Face ID is approximately 1 in 1,000,000 (versus 1 in 50,000 for Touch ID). "

Read this document if you think your Apple ID has been compromised. -->

If you think your Apple ID has been compromised - Apple Support

For iOS 15 or earlier, if you want to see if anyone else has access to your device or accounts, click here --> See who has access to your iPhone or iPad - Apple Support

For iOS 16 or later see how Safety Check on iPhone works to keep you safe. How Safety Check on iPhone works to keep you safe - Apple Support

Use the information in this document to check your Apple ID device list to find where you're signed in --> Check your Apple ID device list to find where you're signed in - Apple Support

Related materials:

Personal Safety User Guide

Personal Safety User Guide - Apple Support

> open the Table of Contents and review the articles

A document with general information about security and your Apple ID --> Security and your Apple ID - Apple Support

Contact Apple for help with Apple ID account security by clicking on this link --> Contact Apple for help with Apple ID account security - Apple Support "This article provides country-specific Apple Support contact information for customers seeking help with their Apple ID password or other security-related issues."

No, they can't unlock your phone without the Passcode or your Face.