Export views result as json, xml, csv etc?
There are some options to export Views data in CSV format in Drupal 8


Views Data Export Module



  This module is designed to provide a way to export large amounts of
  data from views. It provides a display plugin that can rendered
  progressively in a batch. Style plugins are included that support
  exporting in the following types:
  
  
  CSV Microsoft
  XLS (or really simple HTML understood by Excel)
  Microsoft DOC 
  Basic TXT
  



VBO Export Module it adds CSV export feature for Views Bulk Operations  Moule



  The module adds 2 new Views Bulk Operations actions: Export to csv and export to Excel.


3.CSV Serialization Module 

This module provides a CSV encoder for the Drupal 8 Serialization API. This enables the CSV format to be used for data input and output in various circumstances. For example:


  Drupal 8's REST module can accept or return data in CSV format Views
  can output CSV data via a 'REST Export' view Module developers may
  leverage CSV as a format when using the Serialization API