Large-scale tree planting can remove some CO2 from the atmosphere, but nowhere near as much as humans add by extracting and burning fossil fuels. See https://skepticalscience.com/1-trillion-trees-impact.html for a detailed assessment of what this looks like.
The IPCC has a chart showing what actions need to be taken over the next few years. Afforestation is one piece of many things, all of which we need to do.
I’m still down to see them try. We could always use more trees and a trillion seems like a fine addition to our collection.
I’m worried this is an excuse to divert funds away from more practical solutions