Resize an anchored object
Before resizing an anchored object, make sure that you deselect the Prevent Manual Repositioning option in the Anchored Objects dialog box.
Use the Selection tool 
or
Direct Selection tool 
to
select the object, and then drag the side or corner handle.
Note: Vertically resizing inline or above line anchor markers
might result in the object becoming overset. If the anchor marker
is overset, the object will be overset as well.
Resizing an anchored object might also reposition the object. For example, if you’ve aligned the right side of an object to the left side of the text frame, and then you drag the object’s right side handle 1 pica to the left (away from the text frame boundary), the object will resize and then move back 1 pica to the right.