Google developers presented an application for children called "YouTube Kids", which works on Android and iOS. This application has special settings with which parents can protect their children from watching unwanted videos. For example, I will show only cartoons and educational videos.
Also, in the application, you can disable the video search function and it will not recommend videos on unwanted topics. Advertisements while watching the cartoon will not disturb the child, because it was simply turned off in this application.
All the content has been divided into several categories namely Education, Adventure, TV Shows and Music.
An additional advantage is that you can set YouTube Kids for a certain amount of time, after which the application will automatically turn off. YouTube Kids is currently available to users in the US, but will be localized to other countries in the near future.