Find and install the .so shared library a certain version in Arch pacman

How to find and install the .so shared library a certain version in Arch pacman or anything else, e.g. if has such problem;

error while loading shared libraries: libre2.so.7: cannot open shared object file

The fact of the condition is:

$ find /usr -regex '.*libre2\.so.*'
find: /usr/lib/firmware/b43': Permission denied
find: /usr/lib/firmware/b43legacy': Permission denied
/usr/lib/libre2.so
/usr/lib/libre2.so.8
/usr/lib/libre2.so.8.0.0

Don't have the needed but instead having the newer not needed one
Anyone please shed some light on this