Display content based on URL
You can use as an example the taxonomy term view, which is in the D8 standard installation:

admin/structure/views/view/taxonomy_term


Two steps are necessary. First define the parameter in the path. For the taxonomy term this is:

Path

taxonomy/term/%
 ‎
This view will be displayed by visiting this path on your site. You may use "%" in your URL to represent values that will be used for contextual filters: For example, "node/%/feed". If needed you can even specify named route parameters like taxonomy/term/%taxonomy_term


Then add a contextual filter in the advanced section, which will process this parameter:

CONTEXTUAL FILTERS
Add contextual filters
Content: Has taxonomy term ID


For the details see the example in your drupal installation. In your case you would use the referenced Pages node id.

If you want to use the view as a block, you cannot define the parameter in the path setting of the page. Then you have to switch in the contextual filter to "Provide default parameter" and configure the parameter from URL.