Maybe you just want to add a sidebar? https://www.dokuwiki.org/faq:sidebar
There are some plugins that basically automate this by simply adding all your pages into a sidebar. I can't tell if that is the right solution for you. I, for one, prefer to have some manual control over what appears in the sidebar and what not, so I prefer to keep this manual.
If so, maybe one of those who use these plugins can give a recommendation... [edit:] for a start, just look at the plugins tagged with "menu": https://www.dokuwiki.org/plugins?plugintag=menu