How to display the ItemList automatically

How to output ItemList through the plugin – the content of the post automatically and point by point, as in the article example? Here it is in the validator (third party site) https://c2n.me/4fBHY9J.png
Here is my article in which the content is displayed through the plugin
https://c2n.me/4fBI00Z.png and headers are set via H3. Yes, I know that in the “Article” block you need to specify where to collect the headers https://c2n.me/4fBI00Z.png and this is set, but the plugin does not automatically collect them and does not structure the data, as in the example, but everything has to be filled manually https://c2n.me/4fBIJH0.png and then the full ItemList markup for the content of the article may appear in the validator.
Maybe another markup plugin is used in the example, or am I doing something wrong?
update: I want to say the following – in the validator, the ItemList is displayed in the Article https://c2n.me/4fBK1M0.png but I still need the ItemList entity separately as content (plus one more item)
And how to auto-complete “Author Description” in Article https://c2n.me/4fBK4kZ.png? And then in each article you have to fill out a new
The task for the plugin is to automatically collect H2-3 headings according to the content of the article and display them in structured data.
Thanks