Currently dealing with this. My top tip - extinguish the narcissist fire by removing attention from their fire triangle. Example, they come to my door. I see them on the Ring doorbell and ignore them. My boundary has been email contact only. I don't respond to anything else.
When I do respond, I respond to the bits I need to, and ignore the baiting. Received a long email yesterday, gaslighting, making demands. I replied with a one line, factual question.
I am doing a lot of work, have read Lundy Bancroft, and currently on a book called "It's not your fault" which is about identifying and healing from Narcissists. You have to remember, from their perspective, ANY attention is good attention. So if you can go no contact, amazing. If you can't, like me, set your boundaries, keep them and don't give in to their needling. They are trying to reassert control - don't let them.
When they come to you with demands, if you have to interact, give them two choices where you are uncovered by the outcome. Just like a toddler.
It is really hard, you are unlearning years of trauma related behaviour. I feel like I am only just starting out, but so far, this minimal contact, low drama and boundaried approach is working.
Good luck 🤞