There is a check box in Tools > Options > Notifications and Warnings for Display the file size confirmation dialog before downloading.
Ensure that is checked, perform your downloads and it is indicated in the Operations Monitor window that pops up what the file size is. You can then base the size of your deployment on the sizes provided within that window.
If you are downloading in bulk (100 MB +) you should be made aware of the number of files you are downloading as well as the required disk space for download prior to download.
Those are the only features within the Protect GUI that would indicate size. Outside of that the recommendation would be to clear the specified download location on the console and do a manual query of the new patches downloaded for deployment.