How to pull the original image from the server. (Avito and others)?

Question

Web development

Task: It is known that after the user uploads 1 file 1 to the site, the server draws a watermark on it. User 2 visits the ad through his browser and wants to pull out the original file 1, but in the console you can only pull out thumbnails without watermarks, and the media consoles provide links only to rendered pictures. It is also known that there are sites that pull originals without watermarks from site-name.
Question: how to pull out the original using the console/code/source?
PS if the task is impossible, then in connection with what, and how the site-service helps to pull out pictures, if it is known (but not sure) that they work on the principle of parsing.
PSS I am adding the condition: it is known that the site-service makes it possible to pull out pictures fromsite-namein real time, and from any ad.
PSSS will buy access to the site in a week, add the code to the topic with a link to g.drive, it will probably be possible to pull it out from there, but most likely it's all about the server

Answer 1

Obviously, there are links to pictures somewhere or their addresses can be compiled according to a predictable pattern, which is what the service site uses after conducting research.
How to pull out - find links or understand the scheme. To do this, you need to use the console/code/source, of course, but also the head. It is impossible to teach this within the framework of a general question, and a specific question will be a task.