FWIW: I use multiple date & time formats in multiple programs. Since I was dealing with this issue in 3-4 programs for years, I just created 1 AutoHotKey program for all the assorted times I use Ctl+Shft+D (2020-09-27) -Alt+Shft+D (Sunday, September 27, 2020) - Ctl+$Numpad0 (22:12 PM) etc.
Took me 15 minutes to learn enough AHK to do it. AHK can actually create just about any “new” feature I want in Obsidian… If I cared to understand it better and make the macro. I suspect AHK is only one of many ways to do this universally.