I know Nekokurages Manga is the main visual guide for the Anime, but the Light Novels are the bible for visual references. I think the difference between the Anime and the LNs shown in this art I found on twitter a while back is very interesting. And to me, it rings very true.

Source

Below is an english translation version of the notes courtesy of google translate:

Over the course of reading the LNs I started out with the mental image of the characters as they are in the anime, which then morphed into the above impression of the characters, of which I prefer the latter.

The Anime is great, don't get me wrong! I wouldn't like the show this much or be so excited for S3 if I didn't like the Anime. I am deeply grateful we get an Anime and its sequels. it's so cool to see it all in motion, so many things are so well executed, the soundtrack is great, and there was obviously great care put into the show. I really like how they give Jinshi big beautiful eyes in the Anime - it gives him that heavenly quality Maomao describes in the novels, and it makes him look his age.

However. As it is an Anime, it can fall into, visually, Dumb Anime Nonsense. Like the way Maomao's sisters lose all human proportion in place of Tiny Waist and boobies, like the execution of certain pivotal character beats to be funny and/or more serious than they are supposed to, like Jinshi's rock hard Anime Abs that make me wanna Die anytime I see them.