Hi @muser
According to my research and tests, there would be "find more on the server" option only when I working with exchange account in cached exchange mode on Outlook 2013 and search the old items that weren't downloaded locally, is it also your case?
If so, as I know, this option would be diaplayed when we couldn't search related items in local data file, but it's not related to which scope we choose, so in order to avoid any version issues, what's the specific version of your Outlook 2013(File>Office account>About Outlook), please first ensure that you have updated to the latest version of Outlook.
Also, for the requirement of "directly get results for 'find related' search in Outlook", as I mentioned above, if we work in cached exchange mode in Outlook, the client would first search from local data file, if you still need search all items directly, we could try to working with cached exchanged mode and keep downloading all items locally or working with online mode directly(File>Account settings>Account setting>choose your account>change>choose if work with cached exchange mode or how much time you need).
If that's not your case, in order to further analyze it, please provide me with more information, so that I could perform more targeted tests on my environment.
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