I have solved the problem myself:
What I did is:
First created single-football_league.php template
where i placed following codes:
<?php while ( have_posts() ) : the_post(); ?>
<?php get_template_part( 'content-parts/content', 'league' ); ?>
<?php endwhile; ?>
Second:
In content-league.php
, I placed following codes, and it works:
$terms = wp_get_post_terms( $post->ID, array('competition', 'session') );
$term_slugs = wp_list_pluck( $terms, 'slug' );
$season = wp_get_post_terms( $post->ID, 'session' );
$season_slugs = wp_list_pluck( $terms, 'slug' );
$args = array(
'post_type' => array( 'football_fixture' ), // profile and letter are CPTs
'tax_query' => array(
array(
'taxonomy' => 'competition',
'field' => 'slug',
'terms' => $term_slugs
),
array (
'taxonomy' => 'session',
'terms' => $season_slugs,
'field' => 'slug')
)
);