I bought myself a 9th Generation 2015 model a few days back as well with a little over 50,000 Km on the odo. I got the usual service done and fixed/secured all lose moving parts to eliminate the unnecessary rattle and vibration sounds.
I was lucky that the car did not need major work. However, there was one continuous rattling sound that was driving me nuts. The moment the car turned on, there was the constant rattle in the cabin.
Yesterday during detailing I finally found the cause.
The previous owner's child had jammed a "Goldfish" coloring pencil in the passenger side aircon vent. The moment the aircon would turn on, the pencil would start vibrating due the vent thrust.

I am glad to have found the source and eradicate it.
Wish me luck in enjoying this lovely machine and please add me to the Whatsapp Group, if there is one.