About 15 cm view distance for smartphones is pretty normal for me (shortsighted with glasses) on websites where the text is very small, e.g. Hacker News.
Size increases, animation decreases (when your iPhone is getting old, turn off animation and behold it operating super fast!), etc can all be found there.
I zoom websites until they "feel right" which is usually something close to "they are as wide as the window I have them in" - HN is a few taps up from "actual size".