it depends on the kind of red chest
if there's a timer check the hinge for blood, see if the chain is ticklish, and see if the chain moved positions, then click if its real or not.
if there's an exclamation point and a missile do the above but don't let the missile touch your mouse cursor.
if there is no timer or missile check the hinge and spam click it if the hinge makes a click sound keep clicking it until it falls off revealing an arrow pointing to the correct answer, if the hinge does not make a noise open the rule book click on the red "???" and scan the qr code with your phone, you shouldn't have to click any links and it will just say "mimic" or "real chest"