At points I have had invisible people in PS4 Battlefield 4 online, and other curious happenings (quad bikes on maps with no quad bikes for instance), so I presume some measure of cheat at least once existed. Don't know about the current state of play, and have less idea about any hidden cheat options (you occasionally see a kind of shadow scene pop up), nor whether any such people, if they even exist, have moved beyond that and into proper aimbots.
Anyway I expect there are three main approaches
1) All in code aimbot.
2) External aimbot.
3) Hybrid aimbot.
1) This is your classic PC style aimbot. Would need access to the code and could calculate things accordingly. Don't know whether it would be forced within the executable or could be done from outside it -- the PS4 is a fairly modern device that can run multiple strands of code at once.
2) It is possible to capture video from the PS4, and thus possible to do some kind of visual processing on it (could be helped by disabled view mode, in the case of battlefield 4 I might use thermal or night vision scopes to simplify the field of view), or maybe some kind of detection if there is autoaim to subtly guide you beyond what the inputs should have happening -- if input on stick is one way then the amount of pixels moved under normal circumstances should be predictable, autoaim would prevent this, and thus you could use either horizon reference points or more local reference points, or both together, to detect unusual movement and compensate accordingly).
3) Simplest version of this would be to replace all the textures with a nice unmistakeable dot on plain background and have the external aimbot aim for the dot that it can hopefully easily see without needing as much potentially unreliable post processing). PC aimbots often do something like this in addition to things above, or indeed they may have to if there are not so many simple vector calculations available to look at as there once might have been in games), indeed if we are talking Battlefield 5 then it, or at least the potential for it, was a reason given by EA for booting Linux compatibility layer peeps recently (
https://www.theregister.co.uk/2020/01/06/linux_ea_boycott/ ).
For 2) then the basic idea is employed here
I don't know how powerful a machine you will need to do this in real time but it is plausible for at least normal mode, especially for just a simple aimbot as opposed to a full movement and everything bot.