DNS blockers are probably the most popular and easy to use 'filters'
"A DNS blocker is a type of software or hardware product that is used to prevent access to certain websites by blocking the domain name system (DNS) lookup requests that would normally be used to resolve the hostname of the website. The blocked sites are often based on a list of predefined URLs, or the blocker can be configured to block specific types of websites, such as those related to social networking or gambling. DNS blockers are used by businesses and organizations to enforce policies and to limit access to certain types of websites. "
I actually run both PiHole and Adguard Home and I use pfSense for my router/firewall software. All three of these programs are free, open source software, but it takes a little bit of tinkering to get them up and running. You can also purchase similar services or devices - an example that comes to mind is Circle, or as several others have mentioned, use DNS blockers from CloudFlare, opensource, etc
Circle is the easiest parental control device and app to manage screen time across all your family’s connected devices. Keep kids safe online: block inappropriate content and set online time limits.
meetcircle.com
What I like about running Adguard Home versus PiHole, besides the fact their both free, is Adguard Home makes it really easy to block services. So basically I have a linux VM that runs AdGuard and in pfSense each device has a reserved IP address. I am able to go in and set what DNS is used for what device and for the grandkids devices, they are set to use the AdGuard IP, because it is really each to block the different services. For other computers and devices, they use PiHole, primarily for ad and tracker blocking