[cpv]

NetGuard. Creates a local VPN through which the internet is routed. Shows the domains each app is accessing, can be blocked per app, or forbid internet at system level (breaks things, require fine tuning).

Also you can configure a non standard DNS (like adguard, which can block some things at the DNS level).

EDIT: or NextDNS, since it comes with some additional features.

[propogandist]

+1 Netguard. It's an essential app, along with Firefox with ad-blocking add-ons.

Netguard by the same dev behind Xpirvacy, which provides dummy data to apps that try to send back all sorts of unique identifiers to the mothership (+apps like facebook).

Most popular apps call facebook IPs at launch, along with other analytics services. It's quite disgusting.

https://github.com/M66B/NetGuard