Have upgraded sierra to High Sierra to allow me to move from Office 2016 (support stopping soon) to Office 2019 for MAC or Office 365 for MAC (or Microsoft 365 for MAC?) to contunue use of XL, Word and Outlook. Can't see 365 Package in App Store.

I'm not sure why the App store apps aren't working but what I always do is download direct from Microsoft: https://support.microsoft.com/en-us/office/download-and-install-or-reinstall-microsoft-365-or-office-2019-on-a-pc-or-mac-4414eaaf-0478-48be-9c42-23adc4716658?ui=en-us&rs=en-us&ad=us

Note that if you search the App store on a Mac for "Microsoft 365" (the new name for Office 365) if does give a result but in that result you still download the apps individually.

I just realized you haven't subscribed or purchased yet. The link for that is https://www.microsoft.com/en-us/microsoft-365/buy/compare-microsoft-365-products-for-mac

The App Store version isn't any different than getting Office directly from Microsoft, which they renamed as Microsoft 365 instead of Office 365.