I hope someone else responds and proves me wrong, but it’s not likely, for the simple fact that it would probably be a publication under WaniKani as a company. There are some customisable kanji templates out there though, even if I think they wouldn’t really help to lower the ‘effort’ barrier since you’d have to make them yourself. What I can suggest is this thread:
That’s a link to the calligraphy tips I mentioned on that thread, but actually, a whole bunch of writing practice books were suggested in that discussion.
If you want a really low-entry-barrier thing to start with, you can follow calligraphers on Instagram and Twitter, and maybe try to imitate them from time to time. Here’s one: https://twitter.com/kayoshodo?s=21
Kayo-sensei does quite a lot of random posts (in English!) about common Japanese expressions and kanji origins, along with fun riddles. She writes everything herself, and a lot of it is done with a pen, which gives you a realistic idea of what can be achieved with fairly liquid, flowing ink. (Think ‘Pilot G2’ or fountain pen.) I don’t always agree with what she says on kanji origins or what makes for ‘good’ calligraphy, but my knowledge and handwriting are based on Chinese sources and a particular Chinese calligrapher writing in a particular calligraphic form, so there are bound to be stylistic differences. (I tend to feel like Japanese and Chinese calligraphers each follow certain general trends, like Japanese strokes usually being finer, but that’s probably just due to a lack of experience on my part.) In any case, she’s definitely a professional, and her posts are clear, fun, and easy to read. 