WP_Query to get posts in a specific tag or has post_format

Try Below Code :-

$query = new WP_Query(array(
'posts_per_page' => 2,
'tax_query' => array(
    'relation' => 'OR',
    array(
        'taxonomy' => 'post_format',
        'field' => 'slug',
        'terms' => array( 'post-format-link' )
    ),
    array(
        'taxonomy' => 'space',
        'field' => 'term_id',
        'terms' => array('16'), // 16 is the code for tag longform
        'operator' => 'IN'
    )
    )
));