Does submitting a sitemap help SEO?
Yes of course. As you know sitemap is the blueprint or the total representation for robots of your website. When you add your site to search console then the crawlers indexed your data based on your sitemap. The crawler indexed data of your website according to the sitemap. If the sitemap is well organized then it will take less time to google or any other search engine bots for indexing your data then your website.
So you can say submitting a sitemap helps your site SEO as well as growth.