block_editor_settings_all

functions.php

<?php
/**
 * Enable Automatic Anchor Tags Generation for Headings
 */
function enable_block_anchors( $settings, $context ) {
    // Enable anchor generation
    $settings['generateAnchors'] = true;

    return $settings;
}
add_filter( 'block_editor_settings_all', 'enable_block_anchors', 10, 2 );