Collocations for accessory - noun

essential, must-have
optional
fashionable, stylish
perfect, ultimate
This silk scarf is the perfect accessory for stylish summer evenings.

fashion, hair
bathroom, car, travel

accessory to
an accessory to murder

an accessory before/after the fact (= a person who knows about a crime before/after it was committed and protects the criminal)
If you were lying to the police, then you have been an accessory after the fact for all these years.