Change the attendee registration default field name.

registration_label_change.php

<?php //Do not copy this line
add_filter( 'tribe_tickets_plus_attendee_registration_iac_fields', 'modify_attendee_fields' );

function modify_attendee_fields( $fields ) {
    // Check if 'Name' field exists before modifying
    if ( isset( $fields['name'] ) ) {
        $fields['name']['label'] = 'First Name'; // Change label to 'First Name'
    }

    // Optionally, you can add other modifications here
    // For example, changing placeholder text:
    // $fields['Name']['placeholder'] = 'Enter your first name';

    return $fields; // Return modified fields
}