For older posts the date is always displayed.
For newer posts, and I think this is only goes back to 30 days, you get something like “3 days ago”, “8 hours ago” .etc
This is so because date & time are an abstract concept, and mentally, you make the connection much faster when you see “7 days ago”, rather than “26th September” (which is the equivalent date for ‘7 days ago’. I had to open up a calendar to figure it out). It would have taken you more time and effort to figure out how many days ago was a post from “26th September” as in my example.
Anyway, if you hover over the ‘7 days ago’ it would display the full date & time. A click on it would do the same thing.