We need context here. If this is being mundanely requested, it should be a period. If it’s something someone’s repeating in confusion or disbelief, it should be a question mark. If it’s an urgent, panic-stricken demand, it should be an explanation mark.
“I need to go to the store to get milk. Give me your car keys,” Reginald told Tomas.
“Give me your car keys?“ he responded, in awe at the audacity of the demand.
“Yes! Give me your car keys!” Reginald screamed at him, losing his short temper.