Take these measures to prevent your kids from stumbling upon adult sites :
THE MOST IMPORTANT THING TO DO
Go the the settings of your device and search for "parental control". This is by far the most efficient and most important measure to take to prevent your kids from accessing adult content. Those tools are widely available and free.
Additionally you can be interested in the other measures below.
ACTIVATE SAFE MODE IN SEARCH ENGINES
Xvideos will never appear in the search results with these filters.
Google :
https://support.google.com/websearch/answer/510
Bing :
https://www.bing.com/account
Yahoo :
https://help.yahoo.com/kb/SLN2247.html
And other search engines that you use.
You can also use https://www.kiddle.co/, a safe visual search engine for kids.
WINDOWS 10 & 11 FAMILY FEATURES
Once your child has been added to your family with a Microsoft account, you'll be able to set up appropriate website and app and game restrictions for their age, set PC time limits, and review their recent activity. Their settings will apply to any Windows 10 or Windows 11 device that they sign in to.
https://account.microsoft.com/family
APPLE PARENTAL CONTROL
With Screen Time, you can turn on Content & Privacy Restrictions to manage content, apps, and settings on your child's device. You can also restrict explicit content, purchases and downloads, and changes to privacy settings.
https://support.apple.com/en-us/105121
GOOLE ANDROID PARENTAL CONTROL
Google Play store is already kind of kids-friendly as they do not allow any porn-related app. But you might want to go further :
https://support.google.com/googleplay/answer/1075738?hl=en
REQUEST A FILTER FROM YOUR ISP
Your Internet Service Provider likely has solutions to filter your internet connection at their level. Contact them to find out.
Note that this will block Xvideos even for you.