That's correct, either pressing F9 or directly the URL will take the webpage into Reader mode.
But after doing that, @wow1 doesn't want to go with UI automation and want something in a single click, therefore I have suggested an extension would be easier, if that is the preference.
Is it possible to automate all these steps with Power Automate by just clicking on a button in the browser or using a keyboard shortcut?
...it's cumbersome to always switch to reader view first, then click on print as pdf, browse for the folder location, then open Outlook to create a new message and browse again for the right folder to attach the pdf.