After effects can use photoshop filters just copy them over to ae folders.
Amway a halftone is relay easy to implement manually, all you do is make a greyscale image of your halftone pattern, for example if its a round dot make it a radial ramp from wite to black at edges. Then copy this halftone parttern to cover eentire image in the shape you want, grid being the easiest and a half ofset one next (you may wish to do this for each color separately). Then sample the halftone area for its average in case of a grid pattern pixelate does the hjob perfectly (in case of a alternating pattern 2 pixelates), then subtract the pixelation form your halftone pattern shape, and apply a gamma correction so that you solidify the shape.
Tips you can rotate the picture before you pixel ate and apply the shapes and rotate back, this way you bet a slated halftone, you can also apply custom filter for shapes such as triangles and becasue of that hexagons.
Now the nice part of this is you can have any kind of halftone! Even swiming fish that turn into fish swimming other way.