On a 320d at that mileage you'd be better of self insuring.
This is true. I had my E90 320d for just over 8 years of which 6 years was out of plan and only had one R9k claim in all that time. That too we were grasping at straws looking for a reason to claim.
My mum also has a white 2013 F30 320d from new with similar mileage and my dad has self insured since it came off plan in 2020. He was considering the warranty from BMW but really not worth it (unless it's like a few hundred bucks a month) if you're able to stash some money every month towards a repair bill that likely may only occur 5 years later.
Service religiously every 10,000km or annually, do your regular replacement of wear & tear items and chances are nothing big will fail anytime soon.