Will 12 moles of co2 or 12 moles of co have higher volume at STP?

Vol of each = (22.4L/mol)(12 moles) = 268.8 Liters

Both have the same volume.

1 mole of 'any' gas at STP occupies 22.4 Liters. So, 12 moles of 'any' gas (including CO2(g) and CO(g) at STP occupy 12(22.4)Liters = 268.8 Liters