The phone has so many options but I can't find how to lock the home screen to prevent accidentally moving icons around.
Go to settings > security > device security > screenlock. You will See options to enable pattern lock, fingerprint, face unlock option as per your requirement.
Also, To avoid accidental touches in pocket you can also use pocket mode
Settings > advance > pocket mode.
Launcher>Preferences>>Home screen>Lock home screen
You can access preferences either through app drawer (top right three dot menu or tap and hold for 2s on your home screen and access preferences from there)