I don’t know how to recreate this, my column header just crops out and if I go to Column Right-Click → Wrap/Unwrap Text, It only works on the rows/cells of that column.
Also, in that template table from the picture, I am unable to unwrap the text inside column header…
You just need to “click & hold” the line separating the names of the fields from the rows of the table and then either pull it down (to see more of the name) or push it up (to see less of the name)
But, there’s a limit : You can’t wrap more than 3 lines … What comes after that will be hidden