I’m trying to find my friends phone with my iPhone

Do you want to find it because it was lost or stolen?

These are the steps you can perform:--> If your iPhone, iPad, or iPod touch is lost or stolen - Apple Support, and/or:--> Use the Find My app to locate a missing device or item - Apple Support

Do you want to find it because you want to track it?

See this article:--> Find friends and share your location with Find My - Apple Support

Regards

Giulio