A group of Microsoft Products and technologies used for sharing and managing content, knowledge, and applications.
The setting shown in the screenshot only allows users to create sites; it does not by itself display the Create site button.
In the SharePoint Admin Center, go to Settings → Site creation and also enable:
Show the options to create a site in SharePoint and create a shared library from OneDrive
Save the change, then check the modern SharePoint start page again. The button will not appear on classic SharePoint pages, and users may also need the appropriate Microsoft 365 group/site-creation permissions.