There’s more CO2 in the air but plants aren’t growing faster (or larger, sorry apocalyptic comic writers) and the reason for this is that plants, like most things, are complex and simply giving them more CO2 won’t guarantee that they grow quickly, nor would it necessarily be a good thing if they do.
Even if plants are sucking up more CO2 during the day, they’re also releasing more at night so there’s just nothing there to grow on. Even for plants that do grow faster with more CO2, that means that they are likely to die faster as well. Which means they aren’t acting as carbon sinks.
The CO2 isn’t bad for plants, they’ll just continue on as they have (or at least they would if not for other climate change related issues) but it won’t necessarily do anything good for them either. However, we can encourage more plants to expand green areas which could help suck that excess carbon up as well.