For the longest time the font rendering in Windows for example was absolutely garbage for kanji/hanzi on screens like most would be using and in that situation, and yes font size generally needed to be larger than it would be for Latin language users. While Windows technically worked for these languages it clearly wasn’t designed for them. This is somewhat fixed in newer releases.

On the other hand the text rendering on macOS has handled those characters considerably better at small sizes for the past couple of decades, which isn’t too surprising because macOS has aimed to replicate printed text with more accurate letterforms ever since OS X was released, as opposed to the pixel snapping technique used by Windows’ ClearType which only plays nice with Roman characters.

Linux/Freetype has been pretty good with Japanese/Chinese for the past decade too, ever since the improved antialiasing algorithm was added in.

HiDPI screens on smartphones, tablets, and laptops handle these characters pretty well regardless of OS because at those pixel densities, text rendering systems can usually render in adequate detail even at small sizes without doing anything special.