How to sort Custom Fields by a value

If you need sorted result by default,you need to query with sort parameters
see https://codex.wordpress.org/Class_Reference/WP_Query#Order_.26_Orderby_Parameters more more

(example from the codes)

$query = new WP_Query( array ( 'post_type' => 'product', 'orderby' => 'meta_value', 'meta_key' => 'price' ) );

Alternatively, you could also easily do the sorting using jquery plugins like tinysort
( see http://tinysort.sjeiti.com/ )

Hope this helps!