Instagram ads are cheap and allow the most hyper-specific audience targeting I know of, if you want to go that way. You just turn your account into a professional account, which is free, make a nice looking post, perhaps beautiful images of the book in a decorated setting, you holding it proudly and pointing at the camera with your tongue out, or some videos of people reading a passage and reacting, etc., set up the ad campaign step by simple step, then boom!! That post is an ad?

If you want to explore the option some more-->

https://justpublishingadvice.com/how-to-promote-your-book-on-instagram/#:~:text=Although%20there%20are%20many%20ways,marketing%20strategy%20and%20book%20promotion.

I hope this helps. Thank you for sharing, and take care!!