I'm pretty sure that Assistive Writing Solutions used to make something very similar, but they went out of business. What I did find, are these (colourful, but not in the exact same way):

Journals/notebooks:

https://www.amazon.com/Pastel-Rainbow-Colored-notebook-rainbow/dp/B09B386W27

https://www.amazon.com/Pastel-Rainbow-Colored-notebook-colorful/dp/B09BFJJLL6

https://www.amazon.com/Colored-Paper-Notebook-journal-Journals/dp/B08KTHWXSL

Freeleaf notepad:

https://www.levenger.com/color-gradient-freeleaf-notepad-17293.aspx

Alternatively, as another poster mentioned, there are these types of notebooks for beginner writers, where the coloured lines act as a guide:

https://www.vikingcompany.net/us/product-category/writing-papers/intermediate-notebooks/