Thought at first you meant enemies with invisible sprites like Intangr from FFVI and that one rare enemy from FFXII.

But on random encounters and turn-based combat, the mainline entries (the numbered ones) have been progressively more action-oriented and static encounters-oriented since XI afaik. Though on combat specifically, the first hack and slash (not counting non-mainline entries) afaik is XV.

But the series is pretty overarching, so if you check the non-numbered releases, or spin-offs of numbered releases, you get things like RTS (FFXII Revenant Wings), tactical RPGs (FF Tactics), souls-likes (Stranger of Paradise), hack and slash (Type-0, maybe Crisis Core), literal movies (Advent Children, Kingsglaive), etc. And whether enemy encounters are random, depends on the game too.

And lastly, feel free to crosspost the question to !finalfantasy too, so you can get more opinions. =)