Small ducks fail in small ways: a squashed foot, a stringy bill, an eye that closes. None of that requires a secret profile. It requires a clean first layer and a speed you can actually cool.
Duck Heroes is not claiming that every model is support-free or tested on your printer. Use the note that comes with a file when you have one. The habits below are general FDM practice for a figure about the size of a large cork.
Before the duck
Wash or wipe the bed the way that surface requires. Dry the filament if it snaps or strings more than it used to. Run a first-layer test that is smaller than your hand. If that patch is ridged or loose, do not start the character.
A brim helps a narrow base. A raft is a last resort on a display piece because the bottom will show it.
Orientation
Put the face where supports will not chew it. If the bill sticks out, try an angle that gives the underside a gentler overhang, or accept supports you can remove without digging into the smile. Eyes should not be the lowest surface if you can avoid it. The capsule shape is the detail people notice first.
Layers and speed
A 0.16 mm or 0.12 mm layer height is a reasonable place to start for a face. Drop the outer-wall speed if corners look melted. Cooling helps bridges and a thin bill. Too much cooling on a tall, narrow hat can split layers. Change one setting at a time so you know what fixed it.
Supports
Use supports for overhangs you have already seen fail, not by default on every surface. Tree supports often reach a bill with less contact than a solid grid. Leave a small gap so they snap off. If a support bond is tearing the surface, tight or stuck parts covers removal without sanding the face away.
After it finishes
Look at the eyes, the bill, the base, and any thin prop. Measure height before you quote a size to a buyer. If the base bulges, read elephant foot before you print the next one.
Then decide if this duck belongs in a set. A first good print is the moment to stop changing settings and save the profile with the model name.