/root is full to the brim and I can't install new packages. My
/home has 8 times the space of my
/root, but pacman is set to install new packages on
/root. Is there a safe way that I can change where pacman permanently installs new packages?
No, there is no safe way to do this in the long term. From the manual:
This is not a permanent solution. You need to backup your data and resize your partitions.
You could also clean pacman's cache (