SMERTH

7.1 Apply Patches Using Composer

For any package within the composer.json listings you can add a patch

@ drupal8-site/composer.json

{
    "extra": {
      "patches": {
        "drupal/admin_toolbar": {
          "Patch description": "/path/to/file.patch"
        }
      }
    }
},

The file could be on D.O, or local, or on Github...