Hi David,
There is no out of box solution to change the page after clicking the SharePoint tile. This SharePoint home page is new experience for Office 365 users. End users can get more information from the new SharePoint home page (e.g. their following site, recent sites, the links added via tenant admin). To learn more, see Find sites and portals in Office 365.
If you want redirect cx to another page or URL, you may add a custom tile to Office 365 app launcher, and then let users add the custom tile to their app launcher. So, when users click this custom tile, it will redirect them to the URL or page which you add to the custom tile.
Note:Users need to have Exchange Online licenses and enable their Exchange Online mail boxes.
Best regards,
Tim