Can't change pm.max_children in wordpress docker container

Question

I\'m using https://hub.docker.com/layers/wordpress/library/wordpress/5.5.1-php7.4-fpm/images/sha256-71351cbdf76810e8ed2e76f3b1263b6996833c4e3a014d7ffe7eeaf06f81e100?context=expl