Variables in post title

Just use the the_title filter to hook into the title content and work with that.

add_filter( 'the_title', function( $title ) {
    // Manipulate the $title as you want and then return that.
    // You can add test conditions such as 'is_main_query' 
    // (https://codex.wordpress.org/Function_Reference/is_main_query)

    return $title;
} );