Can I make get_users() query global?

You can use the WordPress functions apply_filters and add_filters to store and retrieve data, like so:

// The filter callback function.
function so_wp_380975_get_user_args( $array ) {
    
    // (maybe) modify $array.

    // for now, we just return the array
    return [
        'meta_key' => 'mycred_default',
        'orderby'  => [ 'meta_value_num' => 'DESC' ],
        'order'    => 'desc',
        'number' => 10
    ];

}
add_filter( 'get_user_args', 'so_wp_380975_get_user_args', 10, 1 );

// get the stored args from the filter
$args = apply_filters( 'get_user_args', [] );

Note that you can do a lot more, such as passing additional arguments to the filter to modify the args – or a default value, in case the filter returns nothing.

https://developer.wordpress.org/reference/functions/apply_filters/