dogs dealing with ptsd

I, 21F, (I am not a new dog owner) am adopting a decently sized Boston Terrier 1 year old male, named Otis! I’ve been told he has been suffering from PTSD, I wish to be a good dog owner and I am asking for any advice on how to properly support my new pup. We will be living in an apartment, he will have space and there is a park down the road. I want to ensure he feels safe in my apartment and with me. I also would like to know if a behavioral vet specialist is necessary? Thank you so much for anything you can tell me!