How to make Visual Studio intellisense to show the remarks portion of XML comments?
Visual Studio v16.6.5 has an option in "Text Editor > C# > Advanced > Editor Help", called "Show remarks in Quick Info". It was added very recently and was enabled by default, but I haven't found any release notes or documentation about it. I checked version 16.5.2 and it does not have such an option.
When enabled, Quick Info shows the remarks section after adding a paragraph separator (empty line). When there is no summary section, the paragraph separator still gets added before the remarks (not sure if that's intentional).
The returns section is now also similarly shown, after the remarks section, separated by the word "returns". But there does not appear to be an option to disable this one.
Put your cursor over the class/function/whatever that you want to see the full comments on, then press F12. Expand the comments section on the left of the editor pane.