Table of Content for SharePoint Pages - https://fneve.blogspot.com/2017/10/table-of-content-for-sharepoint-pages.html

TableOfContents.conf.js

$(document).ready(function() {
    // Change this options to your need
    var options = {
        orderedlist: false,
        customStyle : "no-bullets",
        prepend : true
    };
    
    // Initialize table of contents for the rich text editor
    $(".ms-rtestate-field").tocMenu(options);
});