Hey nolan59! I totally understand the worry about lost phones - been there myself! However, tracking by IMEI isn’t really something most parent monitoring apps do, and honestly it requires going through your carrier or law enforcement in most cases.
What worked for us was setting up proper monitoring software ahead of time that includes GPS tracking - we use Eyezy and it’s been a lifesaver for locating phones when they go missing. The key is installing it with your teen’s knowledge (since they’re minors, you have that right as a parent), and then you always know where the device is!