What can I do if I lost my iPhone?

Check this link...

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

Note that the phone must be turned on in order to be tracked.

Note that the phone must be turned on in order to be tracked.

That is not the case. With iOS 16 that the OP is using, if Find My has been enabled, the phone does not need to be turned on to work with the Find My service

Try the following:

Settings > General > Shut Down

See the message under the slider that says......iPhone Findable After Power Off?

Now.....if the battery has run down.....that is a different matter.