I gave that many attempts but Windows 7 and Outlook 2010 were the last platforms where WMDC was able to fully sync Windows Mobile 6.1 (in my case) with Outlook. It seems that later versions (of both OS and Office?) simply do not supply compatible libraries and mentioned types of information are greyed out. I tried many ways to resolve this local sync but I wasn't able to resolve it any more.
So I switched to remote sync which worked until Exchange certificates expired: I was able to sync with latest Windows and Office (that time it was Windows 8/Outlook 2013) by purchasing Exchange Server subscription so the phone was using Exchange sync directly to the Microsoft, but support for Windows Mobile 6 was dropped sometimes in 2015 and since that time, this last operational channel is no longer available. (Server-side certificates are kept expired and ActiveSync shows error.)
But using that Exchange subscription you may be able to work on Windows 10/Outlook 2016 while your older Windows 7/Outlook 2010 machine will also synchronize to that Exchange account and in turn it will sync with your phone locally. This way you can go indefinitely long without limits until your old PC works. But it is questionable whether it is worth the effort and money.
Sync using hosted Office 365 solution:
New PC ←syncOverInet→ Exchange server ←syncOverInet→ Old PC ←localSync→ WM 6.x Phone
If you own your own installation of Exchange server, you might still be able to sync your phone directly with it (without need of the old PC) but you must be the administrator of that Exchange server. In standard hosting (like in one mentioned above) administrators won't re-supply expired server-side certificates for sync with WM. If you are an admin of own Exchange server, you might be able to supply them as long as you want. But obviously, certificates for WM are not the same as certificates for newer phones, maybe there is a different sync technology/channel so I'd say that even this way of sync can stop working with some new version of Exchange server.
Sync using your own Exchange server solution:
New PC ←syncOverInet→ Exchange server ←syncOverInet→ WM 6.x Phone