yes it is possible. It is not hard but a complicated cheat. I made aimbot for Assault Cube, in x87FPU Assembly. A friend of mine made it in SSE assembly, but using native trigonometry functions like
for calculations. Another guy made both aimbot and ESP for assault cube in lua.
To make an aimbot, you need to understand how trigonometry works, how angles are calculated, how you can get angles from distances and distances from angles.
Another very important feature about aimbot, (which is actually not a part of aimbot, but almost every aimbot developer introduce it), is aiming at the closest entity. If you ask me, it is the hardest part in developing an aimbot, because it requires you to get the entity base pointer, entities count ,and then iterate through it to get the closest entity, and if you are making an internal aimbot, it might get a lot messy.
ESPs require external overlays, in CE you can use lua to create an overlay for you and then highlight objects/entities using it.