Full page Screenshot
There’s no “Full Page” option on my iphone when I take a screenshot. It only takes a simple screenshot.
I don't use Netflix on my iPhone, so I cannot say. I just tried a screenshot from a website in Safari, and it worked just fine. I recall someone mentioning that this whole page screenshot only works in Safari, but am not 100% positive. I did just try to take a screenshot in another app that was larger than a single page and it does not provide that option for full page either. A web search for this shows that all articles about it mention only Safari web pages for full page screen shots.
EDIT: According this page in the iPhone User Guide, Take a screenshot or screen recording on iPhone - Apple Support it seems there are restrictions on the full page screenshot.