@heidilifeldman Also, disable WiFi, Bluetooth, NFC and location service whenever you're not using them.
[RISKY ]If you still want to have biometric enabled, biometric can be trmporary disabled for once if you quickly press your iPhone power button >5 times, or long press Android phone's power button and choose Lockdown (may not be present on some Android device with manufacturer's customization. Disable biometrics totally if this is the case). HOWEVER, note that it maybe hard to complete when police is coming to grab your phone.
It's VERY RISKY to post pictures taken on protest as it may expose people near you to prosecution. IF you really wanted to, blur/cover others' face first!