Extract Domain related words
One very obvious way is to use gensim's word2vec most_similar() function to get the most related words to the queried word.

You can check an online version of how it works out here: https://projector.tensorflow.org/

Again it depends on what kind of relations you seek. Other useful methods include:

from nltk.corpus import wordnet as wn

wn.synsets('car')
wn.synsets('car')[0].hyponyms()