Yes, the 2008 BMW 535i has Bluetooth as a standard feature.
For earlier model years when the feature wasn’t a given, adding the capability yourself is still easy enough with the right adapter.
Because its availability might vary depending on package options and model years, be sure to confirm whether the specific 535i you’re looking at does have Bluetooth as a feature.
Keep in mind, too, that the 2008 BMW 535i’s Bluetooth feature is mostly for phone calls—if you’re hoping to stream music from your phone, you’d either need an adapter, or you’d want to look at some later model years.