When preparing to encounter a narcissist, reminding yourself of your own self worth and understanding that the person you are dealing with might trigger you can be helpful.
Narcissists love emotional reactions. They perceive them as supply and feed on them to fuel conflict and create confusion and chaos which is the atmosphere in which they thrive. You can take that away by adopting the “grey rock” method: short, unemotional, very objective answers, even if they bait you.