I was having a really difficult time trying to implement the predictive text thing in Visual Studio 2019. It’s called “Intellisense” apparently. I couldn’t find the “Unity Tools” mentioned, but I already had them. If you installed through Unity Hub, they’re there. The solution that worked for me was found here:
https://forum.unity.com/threads/intellisense-not-working-with-visual-studio-fix.836599/
Of course, these things change daily apparently, and everything is outdated. As of today (3/27/21), what worked for me was following the directions in that post:
Close Visual Studio
In Unity, go to Edit < Preferences < External Tools (left part of the Window)
In External Tools go to the part that says External Script Editor, select Visual Studio. (It’s probably defaulted to “Open by File extension”)
THEN click all of the check marks underneath it.
Close it out, and you should be good to go!