I've been reading about K-nearest neighbors algorithm and want to clarify few things.
If we have 2 features we could simply plot it on 2-d plane and calculate distance by using euclidean distance or Manhattan distance.
When there are more than 3 features, exceeding 3-d going into 4-d and more I've read that we use PCA to reduce dimension to 2-D and then calculate distance on PCA plot.
But my question is, is that only way? so in order to use KNN for more than 3 features we must use PCA?