When you stop smoking your lungs do eventually start recovering at least some.
If you've been smoking for only a year or two years or less then your lungs will recover much faster and better than if you were smoking for 20 years or more.
The longer you smoke the more damage you have done to your lungs and eventually if you do too much damage to your lungs then your lungs will never fully recover.
But stopping smoking is a good thing no matter how long you have been smoking.
My dad smoked for 30 years and stopped cold turkey and has stopped smoking for 5 years now and has never touched another cigarette.
His lungs have started recovering some but he has COPD now.
So please never start smoking if you have never smoked or if you do smoke please stop smoking.