Add new field for confirm email field..

confirm-email-field-native-wp-registration-form.php

<?php

add_action( 'register_form', function () {

    $confirm_user_email = '';
	if ( isset( $_POST['confirm_user_email'] ) && is_string( $_POST['confirm_user_email'] ) ) {
		$confirm_user_email = wp_unslash( $_POST['confirm_user_email'] );
	}

	?>
        <p>
        <label for="confirm_user_email"><?php _e( 'Confirm Email' ); ?></label>
        <input name="confirm_user_email" type="email" id="confirm_user_email" class="input" value="<?php echo esc_attr( $confirm_user_email ); ?>" maxlength="200" />
        </p>
	<?php
} );

add_filter( 'registration_errors', function ( $errors, $user_login, $user_email ) {

	if ( $errors->has_errors() ) {
		return $errors;
	}

	if ( ! isset( $_POST['confirm_user_email'] ) || $user_email != wp_unslash( $_POST['confirm_user_email'] ) ) {
		$errors->add( 'email_not_matched', __( 'Email not matched. Please check.' ) );
	}

    return $errors;
}, 10, 3 );