Increasing privacy on Samsung phone with stock rom?

I’m unable to install custom roms on my Samsung phone, and I currently can’t afford getting another phone. The model in question seems to support Android 13 after an update, at least from what I read. However for personal privacy reasons, I would not like to mention the specific model of the phone.
What can I do to improve privacy on Samsung phones with stock roms?

I would probably install rethinkdns, it has tracker filtering via dns and a firewall for apps. If you use a vpn maybe consider nextdns to have the vpn slot free.

I’m probably missing something, but I can’t figure out how to find the hostname for rethinkdns nor nextdns. Looking at the DNS Resolver recommendations from Privacy Guides, I was able to find the hostname for Mullvad’s DNS resolver though. Would that work as well, or is it missing something that rethinkdns/nextdns can do?

Aside from DNS, is there any other settings I should change too?