Google’s robot web crawlers come round to your website all the time. If you’ve got Google Search Console running, you can even see how often. Any new pages, as long as they’re reasonably prominently linked (including through your sitemap) should be found quickly.
Nevertheless, people do get worried that this will take longer than they’d like. There’s long been a way to submit pages directly for Google’s consideration through Search Console (use “Fetch As Google” to check the page then “Request Indexing”). There’s also this page where you can just paste in a URL and Google will – apparently – take a look.
Most recently, that tool has been incorporated into the search results. Just search for “submit url” and you’ll see.
Do consider this nothing more than a polite request for an expedited visit. I’ve seen some good results for getting a page into the Google index, although it’s impossible to say whether or not it would have been added quickly anyway. Still, if you have a checklist of things to do when you publish a new page on your website, it can’t do any harm to have this as an extra step.