/usr/lib/x86_64-linux-gnu/libexpat.so is in libexpat1-dev 2.2.5-3.
This file is owned by root:root, with mode 0o777.
It is a symlink to /lib/x86_64-linux-gnu/libexpat.so.1.6.7
/lib/x86_64-linux-gnu/libexpat.so.1.6.7