The cell has no content, so there is nothing to select.
Images pasted into cells are treated as 'Image Fill', which is format, no content. You can select the cell, press option-command-C to copy that format (and any other format attributes assigned to that cell), then select one or more other cells and press option-command-V to paste the format of the original cell into the selected cell(s).
If you increase the size of the cell, the size of the image will increase to fill the cell in the same manner as it did when inserted in the original size cell.
If you want the central part of the image to occupy more of the cell, you need to trim the unwanted area from the image before pasting.
Regards,
Barry
PS: Adding the same image to several cells in this manner will quickly bloat your document. Pages does not index a single copy of an image to display in several locations, nor does it load a reduced size image to display in a small space (such as a table cell). Each copy is received as a full size image file.
B