This Add-on makes it possible to precisely control the size images in Google docs.
This Add-on makes it possible to precisely control the width & height of images in Google docs. It currently only works with ‘In line’ images. I’m waiting for feedback by the Google API team to make it also work with ‘Wrap text’ and ‘Break text’.
Use the menu Add-ons->SetImageSize. “Set image height” and “Set image width” have shortcuts that respect image aspect ratio. “Show sidebar” gives you more options, including pixel/inch/cm units and setting width & height independently. You get use “Get image size” (I have not found a way to do that when you select the image.) You can also edit the shortcuts for width & height (which will respect aspect ratio).
If you get the error "ScriptError: Authorization is required to perform that action." then maybe you are logged into your browser with multiple accounts and Google script doesn't like that.