/etc/apt/apt.conf.d/20archive is in apt-config-auto-update 2.0.0-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 | APT::Periodic::MaxAge "30";
APT::Periodic::MinAge "2";
APT::Periodic::MaxSize "500";
|