Tracking my child's location on iPhone

Go to Settings > Screen Time > [choose the child's name] > Content & Privacy Restrictions > Location Services. Make sure Location Services is turned on, and also tap Share My Location and verify those options are turned on. After that tap the back button and choose the option to "Don't Allow Changes". Back all the way out to Settings again and that should prevent your child from making any changes.

Another good one to set is at Content & Privacy Restrictions > Account Changes, and make sure this is set to Don't Allow. The will prevent the child from logging out of their account.

If you want to pursue this path, then here is how to restrict changes:

• Family Sharing overview for kids and teens - Apple Support

If your child is disinclined to cooperate however, this tracking effort will fail. The iPhone “lost” or ”misplaced” or “left behind”, or Faraday-bagged, among various other feasible responses.