Help find a family member's lost phone
Help through the family features already configured, or let the owner sign in to their own finding account on a trusted device.
What to do
First, check
Ask the owner what account and family-sharing features are available.
Then
Use the official family-device list or a guest sign-in route where supported, then protect the device if needed.
If it’s not that simple
Help without taking over the account
Configured family access
Use the appropriate authorised device list.
No shared access
Let the owner use a supported guest/owner sign-in on a trusted device.
No working account route
Help with provider recovery and carrier contact rather than requesting secrets for this website.
Good to know
Do not ask the owner to disclose a password or one-time code to this site.
Official source
Apple Support · family location sharing