Depends on the country. People living in richer European countries buy more new cars on average, while people in poorer European countries give second life to those same cars once those "rich people" decide to sell them and fail to buy any buyer domestically.

This is still a net positive even in poorer countries. If you can't afford a new car, you buy as close to a new car as you can afford. The newer the car is, the higher the EURO standard is that it had to abide by when it was sold brand-new, achieving the same result of reducing pollution.

I live in one of those poorer ones where most people can't afford new cars, but even if you can, the percentage of brand-new ICE cars that are even available for purchasing is going down pretty fast in recent years. So those better off are slowly being pushed towards EVs (or at least hybrids), and the vast majority of others still relies on importing like 15 years old second-hand cars (EURO 5 standard) to replace their 25yo cars (EURO 3 standard). In the capital, cars below EURO 4 are even banned when air pollution gets really bad, but the vast majority doesn't even realise this rule exists because their cars are now EURO 4 or above.