Can the MoonBot terminal be set up so that if the entire market starts to fall by more than a certain percentage, for example, after a sharp drop in price, it will trigger an urgent sale of all coins?

Yes, to do this you need to put a tick in the Settings – Autostart tab against the parameter: “Global Panic Sell If all markets avg. rate drops” and below after “Hourly avg. rate drops more than then (%) N” parameter in the field specify the market drop threshold you need as a percentage.