Do you mean zooming or scaling? Zooming changes the layout preview and not the page objects. To scale an image select it with the Direct Selection tool (white arrow) then Shift-drag on its corners, or use the Transform panel to change its scale or dimensions.
With View>Extras>Show Content Grabber on, you will get a center target with the Selection tool (black arrow). In that case you can move the image by clicking and dragging on the target.
I don't know what is the correct terminology, but none of those things does what I want. With the Content Grabber I can move the image and see where it is going and place it where I want it, and the frame does not move and is not changed in any way. I want something that does exactly the same thing with "zooming" in and out on the image.
Shift-drag on the corners moves the frame. In the Transform panel, in the lower box, it makes the image AND the frame larger or smaller. Neither of these is what I want.
If I'm not using the right terminology, let me try to explain. If I have an image that is larger than the frame, then I can only see a small part of the image inside the frame. If I could zoom out on the image, I would then see a larger part of the image in the frame, but the frame would be exactly the same size and in exactly the same place (just like it would be when you use the Content Grabber). If I could zoom in on the image, then I would see less of the image but in more detail.
If I could move (like the Content Grabber) AND zoom without doing anything with the frame, then I could get the image just the way I want it inside an already-properly-placed frame in the most straightforward and simple manner, and be able to see what I was doing in the process. Dragging on the corners is basically trial and error because you have to go through several steps before you see the final result.
If you are seeing the Content Grabber then you are using the black Selection tool with the container frame selected. Use the white Direct Selection tool (shortcut is A) to select the image and not its container.
The content of a frame has its own bounding box—the frame and content are separate objects:
Drag on the corner of the image and not the frame. After you start the drag add the Shift key to constrain and then the Option key to scale from the center of the image.
Ah, I see the difference now, and dragging on the corner of the image instead of the frame does zoom the image without changing the size of the visible image or the size or position of the frame that it is in. Thank you!