https://docs.magento.com/m2/ce/user_guide/cms/pages-default.html

Default Pages[標準のページ]

The Default Pages configuration determines the landing page that is associated with the base URL, and the corresponding home page. It also determines which page appears when a “Page Not Found” error occurs, and if a breadcrumb trail appears at the top of each page.

標準のページの構成はベースURLに関連付けられたランディングページとそれに対応するホームページを決定します。エラーページやパンくずリストの表示等を決定します。

To configure the default pages:

1. On the Admin sidebar, tap Stores. Then under Settings, choose Configuration.
2. In the panel on the left under General, choose Web.
3. Expand  the Default Pages section. Then, do the following:
a. In the Default Web URL field, enter the relative path to the folder in the Magento installation that contains the landing page. The default value is “cms.”

For a specific store view, clear the Use Default checkbox next to the Default Web URL field, and any other default fields to be changed.

b. Set CMS  Home Page to the CMS page to be used as the home page.
c. In the Default No-route URL field, enter the relative path to the folder in the Magento installation where the page is redirected when a “404 Page Not Found” error occurs. The default value is “cms/index/noRoute.”
d. Set CMS No Route Page to the CMS page that appears when a “404 Page Not Found” error occurs.
e. Set CMS No Cookies Page to the CMS page that appears when cookies are disabled in the browser.
f. If you want a breadcrumb trail to appear at the top of all CMS pages, set Show Breadcrumbs for CMS Pages to “Yes.”
4. When complete, tap Save Config.