First off, it's called robots.txt -- you don't make it plural, it doesn't do anything.
Second, it exists to block off access to links and directories so they aren't indexed, that's all it's for. As such, it's the OPPOSITE of SEO in that it's designed to make search NOT pay attention to the content it's masking off!
Third, it has absolutely NOTHING to do with what a sitemap is.
Though if we're going to talk 'sitemaps' if you have every page on your site linked to by at least one other page on the site -- aka building a site properly, there is NO reason to build a sitemap or submit it to Google. It's a bunch of bekaptah nonsense that has never served a legitimate purpose.
Finally, on the subject of BOTH robots.txt and the REL attribute, there is no such thing as "follow" and "index" no matter how many people use them out of ignorance, the only valid properties are "nofollow" and "noindex". If you want things followed or indexed, don't include the properties... or the attribute... or the robots.txt file.