An example that shows how to conditionally not include a registration form question when a specific ticket is in the cart. Event Espresso 4

conditional_question.php

<?php
//* Please do NOT include the opening php tag, except of course if you're starting with a blank file

add_action( 'wp_enqueue_scripts', 'rc_ee_hide_custom_questions_convention', 99 );
function rc_ee_hide_custom_questions_convention() {
    wp_add_inline_script(
        'single_page_checkout',
        'jQuery( document ).ready( function( $ ) {
            if($("#spco-attendee_information-dv").find(".spco-attendee-ticket-910").length !== 0) {
                $(".ee-reg-qstn-34-input-dv").hide();
            }
        });'
    );
}