The standard template page doesnt contain a sidebar.
You have to make another template page in a child theme where you can add it.
ctron – The Sidebar widget area in Twenty Seventeen displays widgets on single posts, but not the front page or static pages.
If you want to add a sidebar — either the existing one or a new one — to static pages, you’d need to create your own custom template in a child theme, as project13x mentioned.
Here are some resources if you’d like to go that route:
Custom Templates
https://developer.wordpress.org/themes/template-files-section/page-templates/#creating-custom-page-templates-for-global-use
Child Theming
http://codex.wordpress.org/Child_Themes
https://www.smashingmagazine.com/2016/01/create-customize-wordpress-child-theme/
If you need further help with it, just let us know.
Just wanted to add that you don’t need to create a custom template unless you want the option only to select a sidebar layout on certain static pages, and not all pages. If you want the sidebar to appear on all pages, then you could just add the call to your sidebar in page.php in your child theme, and it would apply to every static page.
