How do you find site usage statistics in SharePoint Online?
In the SharePoint Admin Center, select the SharePoint File Activity report.
On the Site contents page, click Site usage.
On the site home page, click the gear (Settings) icon and go to Site information. Select View all site settings, and then in the Site Administration section, select Site usage statistics.
On the site home page, click the gear (Settings) icon, go to Site settings, and select Site usage.