I owned a 2017 from zero meter and sold the car in 2023 with 85000 km. Yes it had a steering rack rattle which was replaced under warranty. It had a freezing cold ac which never required any attention in my ownership. I believe that the best thing one can do to protect the ac evaporator is to always keep the fresh air vent closed.
At least, I have not come across any comments regarding CVT failures being an issue with this generation of Civic. The manual calls for CVT oil replacement around 40,000 km. The car you buy, make sure that the services have been done at the proper intervals. If you are completely unfamiliar with this generation's service intervals, I would suggest to visit a 3S dealership and have a chat with any one of the service advisors with the 5000km, 20000km and 40000km service menu. After 40,000 it repeats again.