A well-rounded storefront is going to have a number of custom pages, which is important for building trust with a user. Have you made a purchase from a website that had only two or three pages? It helps a customer see a website as legitimate if they see more than a couple of pages, even if the customer doesn't end up clicking on them.
A few examples of pages you might want on your site:
Terms of Service
Create a Custom Page
Creating a custom page is different from customizing your theme. It won't appear under the Customization section under your theme nor will you be able to use the theme editor to enable blocks for the custom page. This page is essentially hidden unless you place a link to it somewhere in your theme. You can see how to set up navigation and link to custom pages here.
To create a page, navigate to the Customization tab, select Pages, and click +New Page.
Note that what you enter as the Title will be converted for the URL, so a page called Contact Us will end up with a final URL like https://yourstore.com/pages/contact-us.
If you forget what the URL is or you change the title after creating it, you can click Advanced to see the URL.