Modern SharePoint - add side bookmark menu

I have a Modern SharePoint page that has a navigation menu at the top, which can't change as it's standard across all SharePoint sites The desire is to have a sub menu on the right side of one page that has HTML hyperlink bookmark to a point down in the page. I need to know how to create the right side menu in modern SharePoint, as I do not see a widget that supports this type of request, AND I need to know how to add the HTML bookmark tags down inside the page.