If you're using Android you can automate lockdown mode using Tasker so that it can it can be enabled "passively". For example, on my phone lockdown happens after: too many incorrect access attempts (bad biometric or passcode), any Bluetooth disconnects, any sudden shakes or jolts. So if someone takes my phone away from me, takes my phone from my car, or if I turn off my watch then lockdown. If someone fails to unlock my phone: photo taken, synced to cloud, phone lockdown. If my phone gets tapped, set down a little to roughly, or I get thrown to the ground or against a car with my phone in my pocket then lockdown. Sure, it means biometrics is often disabled on my phone, but now I find that reassuring.