Welcome xavve,
This is something we can definitely assist you with, thanks for posting here.
We want to recommend that you check out the steps in this article, as they will show you exactly where you can allow certain websites and block others. This gives you the freedom to customize this feature as you see fit, based on the needs of your child. Here's where to start: Use parental controls on your child's iPhone, iPad, and iPod touch - Apple Support
From that article:
Prevent web content
iOS and iPadOS can automatically filter website content to limit access to adult content in Safari and other apps on your device. You can also add specific websites to an approved or blocked list, or you can limit access to only approved websites. Follow these steps:
1. Go to Settings and tap Screen Time.
2. Tap Content & Privacy Restrictions and enter your Screen Time passcode.
3. Tap Content Restrictions, then tap Web Content.
4. Choose Unrestricted Access, Limit Adult Websites, or Allowed Websites.

Depending on the access you allow, you might need to add information, like the website that you want to restrict.
We hope this does the trick for you!
Cheers.