Not once they are created. However, the combustion process involves combining oxygen from the air with carbon to form CO2. Therefore, every molecule of CO2 means, in theory, one molecule less of O2. Luckily, CO2 content is only about 387 parts per million, while O2 is about 210,000 ppm, so the oxygen content does not decrease by much.
But this effect can be, and has been, measured.
The major constituents of the atmosphere, nitrogen and oxygen, are transparent to infrared radiation and hence don't act as greenhouse gases. In addition to CO2, water vapor is the most important GHG. But water vapor concentrations are highly variable over time, and water vapor isn't found much at high altitudes. These factors leave CO2 with a lot of "control" over the degree of the greenhouse effect.