I’m not sure I understand the question. How to you query posts based on the color_wp value given in my example?
$args = array(
// other query args
// whatever you need
meta_query => array(
array(
'key' => 'color_wp',
'value' => 'red'
)
)
)
$my_query = new WP_Query($args);
see WP_Query https://codex.wordpress.org/Class_Reference/WP_Query