[HELP] How to extrude a PNG

How 3D do you want it? That PNG has transparency so you can just stack a bunch of layers up. Add this expression to position:

[value[0], value[1], value[2] + index]

This will offset each layer by exactly one pixel which is perfect because it precisely lines up with the pixel grid.

Next, make the layer 3D, duplicate once, add a fill to the bottom copy to generate a solid color for the edge because that will probably look better, duplicate about 10 more times, select all but the top layer and duplicate 6 more times. You now have 61 layers. Next, parent all of the layers to the top copy to help keep things lined up, pre-compose, collapse transformations, add a spotlight and some ambient light and then fly your camera around your logo. If you want to animate the logo position you can add a null to the main comp, make it 3D, tie the position and rotation of the top layer in the pre-comp (the parent) to the null by simply dragging the pickwhip between the two timelines. This took me less than 5 minutes and it will render faster than it would if you use the C4-D or Ray-traced (heaven forbid) rendering engine.

OOPS, I made a mistake when I made the screenshot. The expressions should be in the pre-comp. You'll figure it out because I'm giving you the project file: Dropbox - Fake 3D.aep (note: your browser may add a TXT extension to the file when you download it. Just delete that. This is a CC 2018 file) fixing the problem and saving the file took another couple of minutes. Just replace the missing file with your PNG.

The other option - Take your logo into Illustrator, auto-trace it to quickly generate a path around the outside of your logo on another layer, import the illustrator file as a comp. make the layers 3d, convert the vector to a shape, move the shape layer one pixel away from the logo and extrude the shape layer. Illustrator's auto-trace does a lot better job than you can do in AE. That would probably take me about 30 minutes to set up.

If it were my project I would probably use Element 3D or even C4D lite to extrude the logo because you could do a much better job of making it 3D and do some beveled edges. That would probably take close to an hour to get done right.