The video below shows LineageOS running on a Pixel 4.
You can see the interface is no different than any other Android phone. Of course you are free to customize it, with different wallpaper, a different launcher, icon themes, or whatever you like.
Apps are easily installed from either the F-droid store or Aurora. Note that Aurora is a mirror of the google play store, and we wouldn’t necessary recommend any of the apps on their main page due to privacy concerns. But you can find many other great apps such as Brave, MeWe, Protonmail, etc.
We also include a firewall (AFWall) which allows you to block network access for individual apps, as we show.