Can there be an equilibrium between humanity's increase of carbon dioxide output with plants since plants harness CO2?
Yes, with 2 caveats.

More CO2 encourages plant growth up to the local plants' limit. After that limit, the plants are saturated and extra CO2 backlogs into the air. If you intend to prevent atmospheric CO2 buildup, you're better off gradually supplying CO2 rather than deploying it in large surges.

The other caveat is dead trees and other plants that should be harvested or logged to make way for new growth (while providing lumber, fuel, and employment).