A submitted Paper should not have a TOC, and even if it has one, it will be discarded by the publisher.
A Scientific Paper, is not a Book.
Scientific Journals which publish a collection of submitted, and previously peer reviewed Papers create their "ToC" by extracting Paper approved Abstracts.
Serious Journals will also publish Separats. Which are standalone articles of the current volume being published. Alongside they may publish a leaflet of abstracts which you can receive and make a decision if you're going to get the whole Journal or just a Saparat: a single Paper you are interested in, on the field of your research.
Because a Paper deals with one theme; one subject; or one particular problem alone. Two of them, make two separate papers. And will be reviewed separately. And therefore will require a separate entry on ToC of the journal being published.
Why on earth should or would a Paper of a given scientific article have a ToC of its own?!
A typical structure of a scientific paper will or should contain:
Intro (to the subject);
sampling, material(s), method(s), and other technicalities.
Result(s) (+graphs, tables, figures... ).
Conclusion(s) / Summary.
of which, few are mandatory and an optional 2nd, or 3rd language abstract.
And that's all.