Schema markup can help describe what a page is about, but it does not really improve your website structure for long tail keywords. This topic is controversial because there are schema truthers and schema deniers, but Google search representatives have stated that schema is not a ranking factor. In most cases, it helps search engines understand specific elements on a page and can enhance how your listing appears in the search results through rich results. It is more like adding labels to an existing result than changing the underlying strength of the page.
A well structured site absolutely can help you rank for long tail keywords, especially because long tail pages are often deeper in your architecture and rely on internal links and topical relationships to get discovered and earn authority. But schema markup does not equal better site structure. It does not pass authority, it does not create stronger internal link pathways, and it does not replace the fundamentals.
If you want to improve structure for long tail rankings, learn PageRank, understand how authority flows through internal links, and map your topics strategically. Build content clusters, link them intentionally, and support important pages with relevant backlinks. I lean more schema skeptic than schema homer.