in The Firm its obvious in a few scenes they wanted him to look taller than gene Hackman who is around 6'2"
I'd have to rewatch it, I don't recall that
I've been watching the old western TV series The Virginian
. In two-shots Doug McClure as Trampas (over six feet) is somehow the same height as The Virginian of James Drury (well under six feet).
In I Walk Alone
(1947), the first teaming of Burt Lancaster and Kirk Douglas, the former (6'2") towers over the latter by at least 5 inches. But in Gunfight At OK Corral
(1957, by which time Douglas had become a major star), Burt is only about an inch taller.
Some short stars through the years were secure enough to be open about it: Jimmy Cagney, Richard Widmark, Pacino, Paul Newman...
Other stars took pains to hide being short: Stallone, Mel Gibson, Bronson, Steve McQueen (in some films; in others he didn't seem to care), James Mason, Richard Burton... The most infamous example was Alan (Shane
) Ladd, who usually tried to block the casting of any actor taller than him. Later when he made a film opposite Sophia Loren, he was generally shot either standing on a box or with her in a ditch. In the other scenes either one or both of them is sitting down, or in one infamous scene on the steps of a church, Ladd stands one step above her.