I think final fantasy at this point is something rooted in Japanese culture like its part of Japan? Its only been few months since I first played this awesome series (end of August/early September 2024) but I can already spot some things final fantasy does everytime
-active battle system
-airships idk why but square or whoever in it had a love for airships to include them in every game
-chocobos
-magic girl always ever since ff2 a girl has to be the magician of the team maria starts with higher magic than firion and gus clearly devs wanted to tell us "THIS CHARACTER IS A WIZARD" , ff4 with rydia and rosa , ff5 with reina having highest intelligence I think again suitable for magician in fact best magician , in ff6 the protagonist IS the magic girl , ff7 with aerith , ff8 I mean they went ballistic with it the sorceress lore and even gameplay wise selphie is the spellcaster of the team followed by rinoa.
-an inventor named cid
Oh and a hell lot of crystals at least the first few games were all about crystals , crystal that crystal there crystals everywhere!
One unique aspect of ff1 is armor being OP its the only ff game that felt like armor is just too good james the warrior kept getting slapped , clawed , mauled , bitten , stabbed slashed and all sorts of attacks just to take 1 damage like wow this is Teutonic knight level of tankiness.
These are I think are core components of a final fantasy game. (Minus the OP armor)