Currently I am trying get together information about Caitians for some RP.
Since we really only know Caitians through M'Ress, the writers of RPGs had a free-for-all when choosing whether she was of average height for a female. Some RPGers decided that male Caitians were bigger. The two Caitians in ST IV don't have manes, so were assumed to be male (ie. opposite to Earth lions), and yes, those were actors of human-like height.
No one at Paramount restricted height extrapolations in the licensed (eg FASA, LUG) and semi-licensed ("Star Fleet Battles") game manuals and, when Richard Arnold was involved in vetting the licensed tie-ins, he asked DC Comics to stop referencing TAS altogether.
Shane Johnson's "Worlds of the Federation" does suggest heights for Caitians, IIRC. (One of the last books to slip through under Richard's tenure - until Roddenberry's death when TAS references started turning up again.)
get to choose! If you want a towering Caitian in your RPG, there's certainly enough wriggle room in the Memory Beta
references. If you want a diminutive one, go for it.
You're not the first person to venture such a query:
Lots of the comments are inaccurate, though.