A couple of months ago, Google introduced guide and ruler controls for object positioning and text alignment. Now they've added new controls that let you adjust the size and position of shapes, images, text boxes, and other layout elements in Google Slides. Specifically, you can now:

• Set exact object sizes by numeric value or percentage scale
• Adjust the position of objects in a slide
• Rotate objects by flipping horizontally or vertically, or by setting a specific rotation angle

Learn more at https://gsuiteupdates.googleblog.com/2018/06/improved-slide-layouts-with-new-size.html.