WordPress at a glance
function is not described

wp_check_comment_data_max_lengths() WP 4.7.0

Compares the lengths of comment data against the maximum character limits.

No Hooks.

Return

WP_Error/true. WP_Error when a comment field exceeds the limit, otherwise true.

Usage

wp_check_comment_data_max_lengths( $comment_data );
$comment_data(array) (required)
Array of arguments for inserting a comment.

Code of wp check comment data max lengths: wp-includes/comment.php WP 5.2.1

<?php
function wp_check_comment_data_max_lengths( $comment_data ) {
	$max_lengths = wp_get_comment_fields_max_lengths();

	if ( isset( $comment_data['comment_author'] ) && mb_strlen( $comment_data['comment_author'], '8bit' ) > $max_lengths['comment_author'] ) {
		return new WP_Error( 'comment_author_column_length', __( '<strong>ERROR</strong>: your name is too long.' ), 200 );
	}

	if ( isset( $comment_data['comment_author_email'] ) && strlen( $comment_data['comment_author_email'] ) > $max_lengths['comment_author_email'] ) {
		return new WP_Error( 'comment_author_email_column_length', __( '<strong>ERROR</strong>: your email address is too long.' ), 200 );
	}

	if ( isset( $comment_data['comment_author_url'] ) && strlen( $comment_data['comment_author_url'] ) > $max_lengths['comment_author_url'] ) {
		return new WP_Error( 'comment_author_url_column_length', __( '<strong>ERROR</strong>: your url is too long.' ), 200 );
	}

	if ( isset( $comment_data['comment_content'] ) && mb_strlen( $comment_data['comment_content'], '8bit' ) > $max_lengths['comment_content'] ) {
		return new WP_Error( 'comment_content_column_length', __( '<strong>ERROR</strong>: your comment is too long.' ), 200 );
	}

	return true;
}