Help please!! Can anyone tell me how to construct this image please. (without using autotrace). I'm sure there's a way of adding an effect to a bitmap?

I am not aware of an automagical way to do that in CorelDRAW.

It's certainly the sort of thing that a macro could be written to do.

If it's just the image you show - and not the same idea extrapolated to something much more complicated - then I can do it manually without too much trouble using Snap to Grid and Space-bar-while-dragging to drop multiple copies of a shape.

I created a Symbol for each different size of dot (except for the one in the center). So, after laying it out, it's easy to tweak one particular dot size, and have that change applied to each instance of that Symbol.

Create a radial gradient and then run the pointilizer (CorelDRAW 2018) over it. Afterwards you can fill the result with the desired color. Then put the area of interest in a powerclip to make it look square. With some tinkering with the settings I got this result:

Not dot in the center but I consider this as pretty much close.

Ok, got it now correctly. You achieve this result with blending. See my picture below that explains it. You start with three circles in three sizes. First follow the blue blending directions, all with amount "2". Exception is pic 2, there you copy the top circle to the left. The last pics show that after completing one quarter, you rotate it 90 degrees with three copies and you are fine.