With mixhost, you can use WordPress' multisite functionality.
I will explain how to add a site in the subdirectory type.
After successfully installing on multisite and logging in to the management screen, the dashboard will be displayed as shown in "Fig. 1" below (WordPress 5.8.2 display example)
(Fig. 1) Management screen with multisite functionality
(Fig. 2) Management screen without multisite functionality
How to add a site
STEP 1: Click Participating Sites > Site Network Management > Sites on the upper left.
STEP 2: Click the Add New button.
STEP 3: Enter the information and click the Add Site button.
site address
Please enter any character string.
site title
Please enter any character string.
Site language
Please select Japanese.
Admin email address
Please enter any email address.
The following screen will be displayed when it ends normally.