A little improvement for advanced search feature of Gmail with direct filter for the file size has been done recently.
Advanced search with Gmail is the most accomplished feature with the use of operators directly in the main field of research. This requires the use of search operators whose list is available on this page.
It is not always practical for the average user who wants to perform an advanced search, but certainly remains basic. To overcome this inconvenience, a small arrow to the right of the search box to display a form with predefined options of Advanced search has been implemented.
This week, Google announced the appearance of an additional option in this form to search for emails based on their size. Still easier than having to remember the size as operators and larger.