A robots.txt file tells crawlers which parts of a site they may request. It does not guarantee indexing by itself.
Broad disallow rules can block CSS, scripts, or important sections by accident. Specific rules are usually safer.
When you change robots.txt, test the paths that matter most: home, product pages, blog posts, and key tools.
Remember that a blocked URL may prevent crawlers from seeing a page-level noindex tag, so coordination matters.
Use a robots tester to check a path against your rules before you publish changes to production.