Hello and welcome to Apple Support Communities Scribe777,
We see that you're trying to prevent an app from being downloaded by a child. We certainly understand your concern, and we'd be happy to help.
If you do not already have restrictions set up with parental controls, you can do so with the link below, if you choose.
Use parental controls on your child's iPhone, iPad, and iPod touch
You can also prevent them from reinstalling the app by using these steps, Settings > Screen Time > find the chid’s device > Content & Privacy Restrictions > iTunes & App Store Purchases > Installing Apps > Allow/ Don’t Allow.
Thank you for using Apple Support Communities.