Blogger vs WordPress Blog

That capability is not found in the Rowling theme and you can confirm that. Every theme has a detailed theme description page. This one is at https://wordpress.com/theme/rowling and that's where set up instructions for it and the live demo site link is found.

All support docs are at https://en.support.wordpress.com/ where we have a search box as the most prominent feature on the page.

re: switching themesThemes are just "skins" on WordPress.COM hosted blogs.Note that switching themes https://en.support.wordpress.com/themes/#switch-themes can be easily done, provided you are logged in as Admin under the same username account that registered the site, you to

http://NAME_OF_BLOG.wordpress.com/wp-admin/themes.php

*Replace NAME_OF_BLOG in that URL with the actual name of your blog. wp-admin/themes.php

We have a preview function. No content is lost when switching themes on WordPress.COM hosted blogs. It does not matter if the site is private or public.

Provided you are logged in as Admin under the username account that registered the site go to https://wordpress.com/themes and type in your key words, or the name of theme.

If you are not logged in under the correct WordPress.COM username account then clear your browser cache https://en.support.wordpress.com/browser-issues/#clearing-your-browser-cache and cookies https://en.support.wordpress.com/browser-issues/#clearing-wordpress-com-cookies prior to logging into another account

If you did not register the site and do not have the required access you need to contact the person who registered the account and site under it and have them either act, or transfer the site to your username account by using this process. http://en.support.wordpress.com/moving-a-blog/#transferring-your-blog-to-another-user-or-account

The theme customizer https://en.support.wordpress.com/customizer/ provides a preview function for exactly that purpose ie. so you can view what a theme will appear like prior to changing one.

Source: How to show blog excerpts on main page - Rowling Theme