I want to join in here, and I speak not about the app, but the website tiktok.com
Tiktok is very easy to go around. You can choose to have only "allowed websites", and you dont need to add tiktok. Just enter tiktok.com and it will be blocked, but refresh the site and you are in. Then you can search for searchwords that are not appropriate for children. I remember that it was better blocked before, and I think its a change in safari settings somewhere. You might remember that before you could read an article in safari, and if there was a link to an tiktok video, it would not show the video, just a white frame.
Now its shows the video and you can click the video and you are taken into tiktok.com. On ipad you are even more free to use, since on an iphone they will constantly try to push you to sign up. On ipad you easy work around this.
By the way, twitter is also allowed this way, and twitter are known for not having minimum restrictions on whats posted.
I might have found the root of the issue...
if you download Edge and you try to open tiktok.com, its not working, even if you refresh it many times.
This article is an interview in Norwegian where there is a tiktok video linked in the bottom of the article. If you open this in Edge, you can now accesss tiktok. Close Edge, and open it again, and you have access to tiktok. So some settings are changed when the tiktok link is clicked through an article.