Hello, and welcome to Apple Support Communities saffanic,
We can see you've been using Use Screen Time on your iPhone, iPad, or iPod touch, and would like to set up multiple downtime windows for your kids.
We'd like to share this guide because it is a really good resource for you: Set up Screen Time for a family member on iPhone. We like it because it has everything all together with links including suggestions on how to set up the Screen Time passcode under the "Important" section. While we don't see a way to add additional time frames for days, you might want to test out adding different restrictions to make this work. As an example, you can add Downtime for the times you think would work best but also set limits on specific apps that you'd rather they not use separately. Once finished, test it out.
We'd also like to share this: Product Feedback - Apple You can provide Apple feedback about how you'd like to use Screen Time by using multiple time frames.
We hope this helped.