Drupal 8 Apply Custom Theme To View
Drupal 8 views doesn't have a Theme: Information section, or at least it doesn't have information about themes. 

Twig is the themeing engine, so you'll need to get information there. You can enable twig debugging in a services.yml file:

parameters:
  twig.config:
    debug: true


This will print out theme-able names for views in the html. On a site I'm looking at the print out only gives one option for the view: 

&lt;!-- BEGIN OUTPUT from 'themes/custom/sitename/templates/block--views-block--our-leadership-senior-management.html.twig' --&gt;


But the block that holds the view has a number of options:

&lt;!-- FILE NAME SUGGESTIONS:
x block--views-block--our-leadership-senior-management.html.twig
* block--views-block.html.twig
* block--views.html.twig
* block.html.twig
--&gt;


The x indicates that's the template I'm using.