I've always thought they seemed huge on the ground, but I've only seen young ones on the ground. Then I just read that younger eagles can look bigger than adults due to longer, fluffier feathers.
As far as I know, thats true, the younguns are in fact larger due to longer feathers , its ordinary for adult raptors to have more trim feathers than juvs , same as its functional for the males to be smaller and more maneuverable in the air, with females being able to dominate food items. If you look at wing outlines in flight, you may note the older feathers being replaced by shorter adult feathers.
In this photo its clearer that its a juv bald , with the oversized bill , usually the head on juv goldens is slightly paler than the rest of it , while for balds , you can see the breast feathers are in fact lighter- whiter at this stage , than the head is.