How can I find image style SRC from within twig template in view? Why I can't use {{ file_url(node.field_image.0.entity.uri.value) }} in my custom view 


The result not like /drupal-8.6.1/sites/default/files/2018-10/gen9C52.tmp.jpeg
Why I can't use {{ file_url(node.field_image.0.entity.uri.value) }} in
  my custom view


Simply because your view does not have access to the node variable object.

You can use Image URL Formatter module. Then add your image field and for formatter select Image URL.