Set config options per page

Is it possible to set config options per page?

Example: Currently, I want to turn on markdown extra for the test page only, not the whole website. Is that possible?

Thank you.

That should be possible via the ready config option:

Thank you.

Already tried that, but the ready option gets entirely ignored.
I must be using it wrong.

return [
  // these options will work
  'debug'  => true,
  'languages' => true,
  'ready' => function() {
    return [
      // these options will be ignored
      'home' => 'blog',
      'markdown' => [ 'extra' => true ],
    ];
  }
];

Iā€™d be very thankful for any advice.

Currently, the home page option cannot be set within the ready option, that will only be possible in 3.4. I would have expected markdown to work (and in my quick test, it does)