When you create an exposed filter for a text field, you can choose the operator from a list. This determines how the keywords entered by the user are used in the filter query.
I was confused by "Contains" vs "Contains any word" and "Contains all words".
Until I found this post by @merlinofchaos:
https://www.drupal.org/project/views/issues/1744880#comment-6383628
Assuming the filter value is 'foo bar baz'
Contains produces a query like this:
table.field LIKE ('%foo bar baz%');Contains any word produces a query like this:
(table.field LIKE ('% foo %') OR table.field LIKE ('% bar %') OR table.field LIKE ('% baz %'))