Arch Linux: 'whatprovides' equivalent option for pacman

I believe pkgfile or pkgfile -s are what you're looking for. For further reference I will direct you to here. The link will show you what other commands you might need a translation for. I hope it helps.

You can also use pacman -Foy file_name, as suggested here: https://unix.stackexchange.com/a/14865/92541

pacman -F file_name for Pacman v5.2.1 - libalpm v12.0.1