I want to change the Wordpress main query on a fixed page.

The following description has been added to function.php:

On a fixed page called season, I would like to rewrite the request parameter y to the main query that retrieves all the articles that hit the custom field year in the channel custom post.

Is it possible to rewrite it to the desired behavior in $query->set?
Is there no problem with the function to hook above?Please let me know.

add_action('init','my_init');
function my_init(){
    global$wp;
    $wp->add_query_var('y');
}
add_action('pre_get_posts', 'my_pre_get_posts');
function my_pre_get_posts($query){
    if($query->is_page('season')&is_main_query()){

        $year=get_query_var('y');
        if($year){
          // I want to write here
        }
    }
}