Hi Ali M,
Re: Are there kids storybook creator Apps for Apple ?
Apple's free Pages app has book formats you can choose from. They are not particularly children's books, yet you can add whatever pictures and words you want, to the ready-made lay-outs, add or delete how many pages the book has etc.
To get an idea if this may be suitable for you:
See the "Introduction to Pages app for iPad": Intro to Pages on iPad - Apple Support
and
Intro to creating a book in Pages on iPad - Apple Support
Eg: says:
"Templates come with place holder text and images that you replace with your own content. Place holders give you an idea of what a book created with this template might look like when you use its text and object styles. You can modify the template however you like and add features like an interactive image gallery for readers to swipe through".
If this sounds like an option you would like to try:
To download the iPad version of the app: https://apps.apple.com/au/app/pages/id361309726?platform=ipad
Here's a link to the complete "User Guide" for Pages for iPad: Pages User Guide for iPad - Apple Support
(Click on the above link, and choose "Table of Contents" to explore the guide.
You can also search for any topic you want more info. on)
All the best :-)