```WP_Query``` uses ```WP_Meta_Query``` and so I assumed (and thought I understood through research) that it calls the ```WP_Meta_Query::get_sql()``` to build the meta query SQL.  

Inside ```WP_Meta_Query::get_sql()``` is where it applies the filter: ```get_meta_sql```

I can't get this to fire.  

I thought it would fire with ```$var = new WP_Query($args);``` but it isn't.  I need to alter the sql before it is run.  A lot of sources specify this hook.  I can't get it to work.

The actual code is long/complicated, I can't even get it to fire with dummy code in a blank plugin.  Just trying to figure out why this hook won't fire where I'm expecting it to.

**Alternatively** - any suggestions on how to alter the WP_Query sql before it's run is appreciated.

I'm referencing: 

 - https://developer.wordpress.org/reference/hooks/get_meta_sql/
 - https://developer.wordpress.org/reference/classes/wp_query/
 - https://weplugins.com/wordpress/how-to-use-get_meta_sql-filter-in-wordpress/
 - https://wordpress.stackexchange.com/questions/403040/query-to-get-result-by-title-or-meta-along-with-tax-query-parameter
 - https://stackoverflow.com/questions/43734845/how-to-give-or-relation-in-tax-query-and-meta-query-wordpress