If the CO2 level increases there will be a positive benefit to plants but with a warming climate then the limiting factor is moisture in areas tipped to get drier--not CO2 levels
In parts of the planet that are tipped to get wetter--- the limiting factor is the influence of pathogens that attack roots and foliage, and leaching of nutrients from soil--that will have a greater influence on plant growth than increasing CO2 levels
Also plants won't have time to adapt to changes in climate and extremes of weather--another limiting factor
Add rises in sea levels then salt poisoning of water tables will reduce fertile coastal soils to near deserts
Your simplistic argument is useless and misleading !
