This code forces an account creation for GiveWP when account creation is enabled

givewp-create-account-checked.php

<?php
function my_checked_create_account() { ?>
	<script>
        jQuery("input[name=give_create_account]").prop("checked", true);
	</script>

<?php }

add_action( 'give_donation_form_after_submit', 'my_checked_create_account' );