Structured data, just because on a webpage, does not affect ranking. It provides search engines with information about the document and directly affects the increase in CTR, clicks, and impressions.
The Google search engine uses structured data, such as Schema.org markup, to process the page. This helps the algorithm determine how content should be processed. As a result, marked web pages look more attractive on the search results page (SERP). For example, instead of a simple meta description, visitors will see additional information, such as rating, or price. It is important to note, such small detail can both way: attract and repel visitors. So it’s worth considering in advance, what type of markup to add on a certain webpage.
Even if the website Rank #1, users can click more on the 2nd website, due to more attractive snippets. So it is a good idea from time to time to monitor the SERP and check out the attractiveness of your snippet.