I am trying to give people useful advice on how to keep their devices safe, but I don't know how to threat model for armed, masked thugs who may kidnap you off the street, then steal, and possibly sell your phone.
https://www.propublica.org/article/videos-ice-dhs-immigration-agents-using-chokeholds-citizens
Always only password lock your phone. No face ID or thumb print unlock unless it also requires a password. You can be required the scan your thumb or show your face, but it is illegal for them to require your password.
I don't know the security of find my phone type systems are, but if you feel they are OK, then sett it up with your family group.
Make sure any family tracking app is setup with no sharing of data and data is only sent encrypted.