Page properties: Settings at page level
If the user has the correct permissions, settings for a page (and in some cases all subpages) can be made in the page properties:

In the "Page" or "List" module click on "Edit page properties"
Some plugins also come with settings, refer to the manual of the extension providing the plugin.
See also
Technically the page properties are the same as the form displaying the page
record from table
pages
. They can therefore be configured by developers
via TCA.
The concrete settings available in the page properties depend on the chosen
Page types,
represented by database field
doktype
.