Visualizing Decision Tree of K-Nearest-Neighbours classifier
$k$-NN does not build a decision tree to classify a new instance, it looks at the class of the most similar examples (the nearest neighbours) in the training set. So, in short, no you cannot get a decision tree from $k$-NN. You can build a decision tree for your dataset directly by using scikit-learn's DecisionTreeClassifier instead if you need a decision tree.