Getting as bad as Venus would require as a minimum crashing a quarter of the entire asteroid belt into planet Earth, and that's assuming there's enough oxygen and carbon in those rocks.
Even if we burned 100% of all biomass on Earth, leaving it dead, it's still not close to Venus, where the "air" is so thick it's passed the critical point and no longer distinguishable from a liquid.
Even if we did that, the day length on Venus is longer than its year.
Even if we burned 100% of all biomass on Earth, leaving it dead, it's still not close to Venus, where the "air" is so thick it's passed the critical point and no longer distinguishable from a liquid.
Even if we did that, the day length on Venus is longer than its year.