Table of contents as a way to promote?

Question

Search Engine Optimization

Hello.
It became interesting, but does the table of contents for articles somehow affect the promotion?
Increasingly, I notice that many sites contain a table of contents in order to additionally indicate keywords. Some have a table of contents inside a div, some have it inside an article, some have it inside a sidebar.
Given the fact that more and more often I see information on the web that search engines are more often trying to select structured sites, i.e. those whose code clearly consists of header, main, article, section, sidebar, footer, in connection with this, the question arose:
Where is it better to lay out the table of contents?
a) inside an article or section, i.e. where the article is.
b) inside the sidebar
c) no difference. The main thing is to be.
ps "Of course, I'm not a professional, but I'm silent about the behavioral factor, because despite the fact that it is inherent, nevertheless, no one has canceled the keywords so far, because I can assume that without keywords, search engines will start pulling out at all all the rubbish from the network)) and then, when requesting "chair", we will see something like: a woman on a chair, buy a chair, a chair is not a table, a chair is an object, etc. (this is like an assumption), but with all logic, the result of the search is more likely to be 0"

Answer 1

If we are talking about semantics, then it is more logical to do it here: a) inside an article or section, i.e. where the article is.
The sidebar is still better left for navigating the site itself, and not one article.

Answer 2

It is better to post where it is convenient for the user

Answer 3

More important, probably, is not the location, but the link factor itself. In the sense that the table of contents is a list of lines "thematic text + link to subsection"...